28,976 results on '"grain growth"'
Search Results
2. How does cold sintering affect the microstructural evolution of high-entropy pyrochlore during pressureless sintering?
- Author
-
Chen, Zixu, Fu, Qing-Qiao, Zhao, Guoliang, He, Jinmao, Gu, Hui, and Xu, Chen
- Subjects
- *
CERAMICS , *KIRKENDALL effect , *SINTERING , *PYROCHLORE , *DRAG (Aerodynamics) , *YOUNG'S modulus - Abstract
The challenge of producing dense fine-grained high-entropy ceramics is hereby addressed by a combined cold and conventional pressureless sintering method for the first time. It provides nearly fully dense high-entropy pyrochlores with better microstructural homogeneity, and only half the grain size of conventional pressurelessly sintered samples with identical density. Both the finer and more homogeneous microstructures benefit better mechanical properties in hardness and reduced Young's modulus. The kinetics and activation energies of both densification and grain growth were quantified and discussed to understand how cold sintering affects the microstructural evolution during the following pressureless sintering. More importantly, cathodoluminescence analysis suggested that cold sintering could cause more defects on the surface of the original particles, which could promote the grain boundary diffusion and have drag effects on grain boundary motion. The lessons learned here offer scientific understanding and technological guidance towards pressureless sintering of dense bulk high-entropy ceramics. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Matrix compositions and their impact on grain growth and strength of oxide ceramic composites.
- Author
-
Almeida, Renato S. M., Rech, Marcelo B. R., Condi Mainardi, Jéssica, Tushtev, Kamen, and Rezwan, Kurosch
- Subjects
- *
OXIDE ceramics , *COMPOSITION of grain , *HEAT treatment , *CRYSTAL grain boundaries , *THERMAL stability - Abstract
Oxide ceramic matrix composites (Ox‐CMCs) are composed of porous matrices reinforced by dense fibers to achieve high damage tolerance. It is generally assumed that their mechanical properties are fiber dominant. However, fiber strength can also be influenced by the surrounding matrix as it can affect fiber grain growth. Fiber–matrix interactions are studied in this work regarding fiber microstructural evolution and composite strength. Minicomposites containing Nextel 610 fibers and different matrix compositions (alumina, alumina–zirconia, and mullite–alumina) are evaluated after sintering and after additional heat treatment at 1200°C for 100 h. Fiber grain growth during sintering is faster in alumina matrix and slower in mullite–alumina matrix. Scanning transmission electron microscope–energy‐dispersive X‐ray spectroscopy (STEM–EDX) measurements show that Si diffuses between fiber and matrix grain boundaries. This outward or inward diffusion of SiO2 leads to the respectively different grain growth kinetics. Grain growth inhibition in alumina–zirconia matrix is only observed after the longer heat treatment, suggesting that ZrO2 diffusion is slower than SiO2. The resultant composite strength depends not only on fiber properties, but also on matrix densification. Minicomposite with alumina–zirconia matrix showed higher strength, while mullite–alumina composites showed higher thermal stability. In summary, the properties of Ox‐CMCs can be tailored by adjusting the matrix composition with the used fibers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Pressureless two-step sintering of ultrafine-grained high-entropy zirconate ceramics with excellent mechanical properties.
- Author
-
Geng, Chang, Su, Xinghua, Chen, Da, Li, Yu, Li, Linlin, Wang, Jianglin, Meng, Leichao, and Zhao, Peng
- Subjects
- *
TOUGHNESS (Personality trait) , *CERAMICS , *SINTERING , *FRACTURE toughness , *ELASTIC modulus , *GRAIN size - Abstract
The challenge of preparing dense ultrafine-grained high-entropy ceramics through conventional pressureless sintering is hereby addressed by a simple two-step sintering method. Ultrafine-grained (Ce 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2) 2 Zr 2 O 7 high-entropy zirconate with 99.2 % theoretical density and 135 nm grain size has been fabricated by pressureless two-step sintering for the first time. Compared to the conventional sintering, two-step sintering provides finer grain sizes and better microstructural uniformity, which yield excellent comprehensive mechanical properties with high hardness of 16.0 GPa, large elastic modulus of 262 GPa and high fracture toughness of 2.8 MPa·m1/2. It is believe that pressureless two-step sintering can be utilized to prepare other high-entropy ceramics with fine grain size and high quality. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Sintering Mechanism of Pure B4C Ceramic Prepared by Hot Oscillating Pressing and with Excellent Mechanical Properties.
- Author
-
Zhao, Ke, Zhong, Weimin, Sun, Mengyong, Chen, Litao, Liu, Dianguang, and Liu, Jinling
- Subjects
KIRKENDALL effect ,BORON carbides ,VISCOUS flow ,FRACTURE toughness ,CRYSTAL grain boundaries - Abstract
Pure boron carbide (B4C) ceramics are sintered by hot oscillating pressing at temperatures of 1700–1900 °C for different soaking times. The densification mechanism, grain growth kinetics, and mechanical properties obtained under these sintering conditions are systematically investigated. It is found that the fully densified B4C ceramic is obtained at 1900 °C within 120 min, possessing an excellent combination of hardness (≈38.5 GPa) and fracture toughness (4.8 MPa m1/2). The densification mechanisms during sintering are as follows: viscous flow at the initial stage (relative density D ranged from 55% to 65%) under 1700 °C; lattice diffusion/grain boundary diffusion at the sintering stage (62% < D$\textrm{ } D$ < 75%) of 1800 and 1850 °C; grain boundary sliding by dislocation motion at the late stage (65% < D$\textrm{ } D$ < 82%) of 1700 °C and the sintering stage (75% < D < 90%) at 1800–1900 °C; and dislocation gliding and stacking faults at the final stage (90% < D < 95%) occurring at 1850–1900 °C. The dislocation motion exhibits a critical impact on the densification process of the hot oscillating–pressed B4C ceramic. The grain growth kinetics at 1900 °C is controlled by grain boundary diffusion. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Effect of Heat Treatments on the Mechanical and Microstructure Properties of Welded API X70 Steel.
- Author
-
Haissam, Aboubaker, Benarrache, Souad, Rahmani, Rabeh Kouider, Mansouri, Tahar, and Benhorma, Mohmmed Elhadi
- Subjects
- *
EFFECT of heat treatment on microstructure , *OPTICAL microscopes , *SCANNING electron microscopes , *PETROLEUM pipelines , *STEEL pipe - Abstract
The world race in scientific research in the fields of petroleum and how petroleum is transported to another place has inspired our scientific curiosity to research the welding bead of petroleum pipelines. This paper is an experimental examination of the response to the effect of heat treatments on the mechanical and microstructure properties of welded API X70 steel. Our study investigates how heat treatments altered the microstructure and mechanical properties of the fusion zone (FZ) in welded pipe steel of grade API X70. It shows microstructures achieved after one heat treatment at 550℃ for 1h, 2h, 3h, 4h and 5h. A metallographic test by the optical microscope and the scanning electron microscope (SEM) as well as the analysis of the samples by X-ray diffraction (XRD) and the measurement of the hardness test was applied to all the samples prepared. The results revealed that the isothermal heat treatment caused grain growth and coarsening reactions in the weld zone and the hardness of weld joints decreased were the main transformations after increasing the temperature of the heat treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. 白云鄂博矿規物相转化与成核生长研究.
- Author
-
陈昌, 韩文生, 冉孟杰, 任国兴, and 陈雯
- Subjects
- *
DISCONTINUOUS precipitation , *LEAD , *NIOBIUM , *HIGH temperatures , *TEMPERATURE effect - Abstract
The phase transformation and nucleation growth behavior of niobium mineral phase in Bayan Obo mine under high temperature melting state were studied. The effects of different temperature mechanism, basicity (CaO/SiO2) and slag modifiers such as NaF, CaF2 and P2 Os on phase transformation and nucleation growth were emphatically investigated. The results show that the melting temperature above 1 400 °C and the crystallization temperature below 1 300 °C are the key to the phase conversion of high grade niobium ore. Control alkalinity between 1. 0 and 1. 3 is beneficial to the formation of single high grade niobium phase and the growth of grain. The addition of about 2% NaF or 2% 一 5 % CaF2 can improve the grade of Nb2O5 and grain coarsening of niobium rich phase. Although P2O5 is conducive to the transformation of niobium into a single high grade niobium mineral phase, excessive P2O5 will lead to sharp refinement of niobium phase grains. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Effect of Y2O3 doping on thermophysical properties and grain growth rate of lanthanum zirconate.
- Author
-
Moaveni, M.J., Omidvar, H., Farvizi, M., and Mirbagheri, S.M.H.
- Subjects
- *
THERMOPHYSICAL properties , *LANTHANUM , *KIRKENDALL effect , *SIZE reduction of materials , *THERMAL expansion - Abstract
Notwithstanding the impressive phase stability and low thermal conductivity exhibited by lanthanum zirconate (LZ), its low coefficient of thermal expansion is deemed a paramount limitation. In the present study, (La 1-x Y x) 2 Zr 2 O 7 with x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, as new TBCs, were synthesized by reverse co-precipitation and calcination method. The XRD and Raman analyses elucidated that the substitution of Y3+ ions occurred exclusively at the La3+ positions. In addition, in accordance with FESEM and DTA findings, the incorporation of Y 2 O 3 has induced a reduction in particle size and an enhancement in crystallization resistance. The evaluation of the coefficient of thermal expansion (CTE) demonstrated a notable improvement following the introduction of Y 2 O 3. Specifically, the CTE of LZ increased from 9.34 × 10−6 °C-1 to 10.5 × 10−6 °C-1 in the case of (La 0.5 Y 0.5) 2 Zr 2 O 7 at 1100oC. Investigations of phase stability following a 50 h heat treatment at 1300oC indicated that Y 2 O 3 had no impact on phase stability. All compounds, similar to LZ, exhibited excellent phase stability. Furthermore, the addition of Y 2 O 3 significantly amplified the grain boundary diffusion mechanism during heat treatment, leading to an accelerated grain growth rate. The grain growth rate increased from 1.7 nm/h at LZ to 2.2 nm/h in the case of (La 0.6 Y 0.4) 2 Zr 2 O 7. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Phase-Field Simulation of Grain Growth in Uranium Silicide Nuclear Fuel.
- Author
-
Pan, Xiaoqiang, La, Yongxiao, Liao, Yuxuan, Wang, Yifan, Lu, Yonghong, and Liu, Wenbo
- Subjects
CRYSTAL grain boundaries ,DISTRIBUTION (Probability theory) ,ANISOTROPY ,URANIUM - Abstract
Uranium silicide (U
3 Si2 ) is regarded as a viable fuel option for improving the safety of nuclear power plants. In the present work, phase-field simulations were employed to investigate grain growth phenomena, encompassing both isotropic and anisotropic grain growth. In simulations of isotropic grain growth, it is commonly assumed that the energy and mobility of the grain boundaries (GBs) remain constant, represented by average values. The calculated grain growth kinetic rate constant, K, exhibits a close correspondence with the experimental measurements, indicating a strong agreement between the two. In simulations of anisotropic grain growth, the values of GB energy and mobility are correlated with the angular disparity between GBs. The simulation results demonstrated that the growth rate of U3 Si2 can be influenced by both the energy anisotropy and mobility anisotropy of GBs. Furthermore, the anisotropy in mobility results in a greater prevalence of low-angle GB distribution in comparison to high-angle GBs. However, the energy anisotropy of GBs does not impact the frequency distribution of the angle difference between GBs. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
10. Precipitate Dissolution and Grain Growth during Solution Treatment of Ce‐Containing 15Cr–22Ni–1Nb Austenitic Heat‐Resistant Steel.
- Author
-
Zhu, Xin, Shi, Chengbin, Zhang, Huai, Liu, Shen, and Ren, Peng
- Subjects
- *
AUSTENITIC steel , *HEAT resistant steel , *CONCENTRATION gradient , *PARTICLE size distribution , *LAVES phases (Metallurgy) , *CERIUM , *GRAIN farming - Abstract
The precipitate dissolution and grain growth during the solution treatment of a newly developed Ce‐containing 15Cr–22Ni–1Nb steel are investigated. The dissolution of eutectic NbC is the result of the elements diffusion along the concentration gradients, and honeycomb (Fe,Cr,Ni,Si)2(Nb,Mo) Laves phase transforms into a more stable Mo2C‐type M2C carbide. As the cerium content is increased from 0 to 0.0630 mass%, the area fraction of eutectic precipitates in forged and solution‐treated 15Cr–22Ni steel is decreased first and then increased. For the steel with 0.0055 mass% cerium content, the substantial reduction in the area fraction of precipitates during hot forging and solution treatment is ascribed to the severe abnormal grain growth. In the case of 15Cr–22Ni steel with 0.0019 and 0.0630 mass% cerium content, the average size of austenite grains after solution treatment is reduced, the multipeak development of grain size distribution is restrained, the range of grain size distribution is narrowed, and the variation coefficient of grain growth, the critical size of abnormally grown grain, and the proportion of abnormally grown grain are all decreased. The variation coefficient of grain growth and the critical size of abnormally grown grain in the steel are increased as the solution time is extended, whereas the proportion of abnormally grown grain presents a general trend of reduction. The established mathematical model of grain growth in the paper can be well applied to predict and control the average size of austenite grains in 15Cr–22Ni steel after solution treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. Grain orientation and shape evolution of ferroelectric ceramic thick films simulated by phase-field method.
- Author
-
Zhang, Yongmei, Li, Qingshu, Yue, Qidong, Wang, Ping, and Liu, Zhenyu
- Subjects
- *
FERROELECTRIC ceramics , *THICK films , *GRAIN , *PARTICLE size distribution , *CERAMIC materials , *CRYSTAL grain boundaries - Abstract
The orientation and shape of ceramics grains was always neglected, resulting in a lot of information during sintering has not been excavated. In this study, a modified phase-field model in order to express the anisotropy of grain boundary energy is developed. The effects of the anisotropy of grain boundary energy on the grain orientation and shape evolution are investigated in detail. The ferroelectric ceramic thick films are prepared by tape casting. The comparison of experiment and simulation results shows that the anisotropy of grain boundary energy results in uneven grain orientation and bimodal grain size distribution. The quantitative analysis of grain microstructures helps to establish a relationship with the degree of anisotropy of grain boundary energy. Our findings provide a new way to judge the degree of anisotropy by calculating the relevant parameters in the SEM images of ceramics materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
12. Enhancement of Abnormal Grain Growth by Surface Quenching Treatment to Eliminate Cu–Cu Bonding Interfaces Using (111)-Oriented Nanotwinned Copper.
- Author
-
Lu, Tsan-Feng, Yen, Yu-Ting, Cheng, Yuan-Fu, Wang, Pei-Wen, and Wu, YewChung Sermon
- Subjects
- *
STRAIN energy , *COPPER surfaces , *SURFACE morphology , *ELECTRON diffraction , *COPPER - Abstract
Cu–Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, the processing temperature must be kept relatively low, preferably below 300 °C. In this study, a novel surface modification technique, quenching treatment, was applied to achieve Cu-to-Cu direct bonding using (111)-oriented nanotwinned Cu. The quenching treatment enabled grain growth across the Cu–Cu bonding interface at 275 °C. During quenching treatment, strain energy was induced in the Cu film, resulting in a wrinkled surface morphology. To analyze the strain energy, we utilized an electron backscattered diffraction system to obtain crystallographic information and confirmed it using kernel average misorientation analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
13. Enhancing core–rim structure control in (K,Na)NbO3-based lead-free piezoceramics via rapid sintering method.
- Author
-
Chen, Ran, Luo, Xinyi, Xing, Juanjuan, Zhang, Faqiang, Lu, Yiqing, Liu, Zhifu, and Gu, Hui
- Subjects
- *
LEAD-free ceramics , *CERAMICS , *PIEZOELECTRIC ceramics , *KIRKENDALL effect , *SINTERING , *CERAMIC materials , *POTASSIUM niobate - Abstract
Core-rim structure has distinct advantage to improve the performances of KNN-based piezoceramics. Whereas the state of the core-rim structure is difficult to control during sintering. Here, the core-rim structured 0.96(K 0.51 Na 0.47 Li 0.02)(Nb 0.8 Ta 0.2)O 3 -0.04CaZrO 3 (KNLNT) ceramics were both obtained by conventional sintering (CS) and rapid sintering (RS). KNLNT ceramics prepared by rapid sintering exhibit more outstanding controllability on grain growth and core-rim structure and can hold the core/rim size ratio in a stable and favorable level due to extended effective range of grain boundary diffusion in densification. Benefiting from the controllable microstructure, the RS method prepared samples show excellent performance. The unipolar strain value of RS-1240 (S max =0.252%) is 2.07 times as much as CS-1110 (S max =0.122%). Large strain, low hysteresis and low dielectric permittivity features make the core-rim structured KNLNT ceramics a potential material for pulse drive applications and demonstrate that the manual precise control of core-rim structure could create many possibilities on materials design. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
14. Influence of annealing treatment on grain growth, texture and magnetic properties of a selective laser melted Fe-6.5 wt% Si alloy
- Author
-
Lulan Jiang, Haijie Xu, Yuhan Zhan, Dewei Zhang, Xuedao Shu, Zixuan Li, and Jinrong Zuo
- Subjects
Fe-6.5 wt% Si alloy ,Selective laser melting ,Annealing ,Microstructure evolution ,Grain growth ,Magnetic properties ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The high-density Fe-6.5 wt% Si soft magnetic alloy samples were prepared using selective laser melting (SLM) technology. Annealing treatments with different temperatures were employed to promote grain growth. The microstructure, texture and magnetic hysteresis loops were characterized, aiming to investigate the relationship between microstructure and magnetic properties. The as-printed Fe-6.5 wt% Si alloy had weak texture and low density of ordered phases, and was featured by coarse grains in the top-view section and columnar grains in the side-view section. After annealing at 800 °C–1000 °C, the textures were slightly weakened, while the grain growth was not significant. Increasing the annealing temperature to 1100 °C led to abnormal grain growth behaviors. The grains of the as-printed Fe-6.5 wt% Si alloy showed randomly abnormal growth behaviors rather than oriented growth, which may be related to the low stored energy and initial size advantage before annealing. After annealed at 1100 °C for 1 h, the abnormal grain growth and the formation of large Goss ({110}) and Cube ({100}) grains resulted in microstructure coarsening and texture optimization. Thus, the corresponding ring-shaped sample exhibited excellent magnetic performance. The magnetic induction B8 is 1.21 T, the maximum relative permeability is 14.71 × 103 and the core loss P10/50 is 11.69 W/kg.
- Published
- 2024
- Full Text
- View/download PDF
15. Grain orientation and shape evolution of ferroelectric ceramic thick films simulated by phase-field method
- Author
-
Yongmei Zhang, Qingshu Li, Qidong Yue, Ping Wang, and Zhenyu Liu
- Subjects
Phase field simulation ,Anisotropy ,Grain growth ,Grain boundary energy ,Ferroelectric ceramics ,Medicine ,Science - Abstract
Abstract The orientation and shape of ceramics grains was always neglected, resulting in a lot of information during sintering has not been excavated. In this study, a modified phase-field model in order to express the anisotropy of grain boundary energy is developed. The effects of the anisotropy of grain boundary energy on the grain orientation and shape evolution are investigated in detail. The ferroelectric ceramic thick films are prepared by tape casting. The comparison of experiment and simulation results shows that the anisotropy of grain boundary energy results in uneven grain orientation and bimodal grain size distribution. The quantitative analysis of grain microstructures helps to establish a relationship with the degree of anisotropy of grain boundary energy. Our findings provide a new way to judge the degree of anisotropy by calculating the relevant parameters in the SEM images of ceramics materials.
- Published
- 2024
- Full Text
- View/download PDF
16. Effect of Re Addition on the Sensitivity to Recrystallization in As-Cast Ni-Based SX Superalloys
- Author
-
Li, Yihang, Jiang, Zhipeng, Li, Longfei, Xie, Guang, Zhang, Jian, Feng, Qiang, Cormier, Jonathan, editor, Edmonds, Ian, editor, Forsik, Stephane, editor, Kontis, Paraskevas, editor, O’Connell, Corey, editor, Smith, Timothy, editor, Suzuki, Akane, editor, Tin, Sammy, editor, and Zhang, Jian, editor
- Published
- 2024
- Full Text
- View/download PDF
17. Effect of External Magnetic Field on Grain Boundary Migration in Non-magnetic Systems: A Phase-Field Study
- Author
-
Bandyopadhyay, Soumya, Bhowmick, Somnath, Mukherjee, Rajdip, Patra, Sudipta, editor, Sinha, Subhasis, editor, Mahobia, G. S., editor, and Kamble, Deepak, editor
- Published
- 2024
- Full Text
- View/download PDF
18. Studies on thermal stability, softening behavior and mechanism of an ADS copper alloy at elevated temperatures.
- Author
-
Liu, Feixiang, Liu, Xinhua, Xie, Guoliang, Wu, Yuan, and Chen, Cunguang
- Subjects
COPPER alloys ,HIGH temperatures ,ALUMINUM oxide ,THERMAL stability ,FLUX pinning ,PARTICLE size distribution - Abstract
• An alumina dispersion strengthened copper alloy exhibits the highest softening temperature of 1203 K and was fabricated by in-situ internal oxidation and reduction method. • The strong pinning effect of the nanometer-scaled Al 2 O 3 particles helps increase the dislocation density and the grain boundary stability even at elevated temperatures. • A modified Hall-Petch relationship was established by introducing the integration of the grain size distribution, which can describe the correlation between softening behavior and the pinning effect of Al 2 O 3 particles. An Al 2 O 3 dispersion strengthened (ADS) alloy with an ultra-high softening temperature of ∼1200 K was fabricated by the in-situ internal oxidation and reduction methods. The evolution of the nanometer Al 2 O 3 particles, grain size, and consequently the softening behavior of this ADS alloy, were investigated by conducting the annealing treatments in the range from 673 K to 1273 K for 60 min. These refined nanometer Al 2 O 3 particles were found to be highly stable at elevated temperatures, leading to the high dislocation density and grain boundary stability of the matrix. The average grain size was found to increase extremely slowly from ∼0.60 μm to ∼0.74 μm with increasing annealing temperatures from 773 K to 1273 K. A criterion for grain boundaries migration and softening was established based on the competition between grain growth and pinning effect of Al 2 O 3 particles. The strong pinning effect of Al 2 O 3 particles was found when the grain size was between the lower limit (about 0.4–0.5 μm) and upper limit (2.18 μm). The occurrence of softening behavior was attributed to the rapid increase of the proportion of grains larger than the upper limit. A modified Hall–Petch relationship was established by introducing the integration of the grain size distribution, which can describe this correlation between softening behavior and the pinning effect of Al 2 O 3 particles. The current study not only sheds light on the further understanding of the softening mechanism of ADS copper alloy but also provides a useful route for designing copper alloy with high softening resistance. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Reactive diffusion at the interface between Cu and Sn–Ag alloys
- Author
-
Minho Oh, Naru Tokunaga, and Equo Kobayashi
- Subjects
Sn–Ag ,Grain boundary diffusion ,Cu6Sn5 morphology ,Grain growth ,Intermetallic compound ,Mining engineering. Metallurgy ,TN1-997 - Abstract
This study investigates the microstructural evolution and growth behavior of intermetallic compound (IMC) layers in the Cu/(Sn-yAg, y = 0.29–2.00 wt%) system during isothermal aging within the temperature range of 433–473 K. Through systematic variations in Ag content, aging temperature, and time, the fundamental mechanisms governing IMC formation and growth in Cu/(Sn–Ag) solder joints are elucidated. The results demonstrate that IMC growth kinetics follow a power-law relationship, with IMC layer thickness increasing systematically with annealing time. The addition of Ag significantly influences IMC nucleation and growth, with higher Ag content correlating with faster growth rates. Furthermore, the temperature dependence of IMC growth rates is investigated, revealing higher temperatures leading to increased growth rates, indicative of boundary diffusion-controlled growth. By calculating activation enthalpies, values of 36.4 kJ/mol for Sn-2.00Ag and 30.2 kJ/mol for Sn-0.50Ag were obtained, providing quantitative insights into the faster growth rate of intermetallic compound thickness in the Cu/(Sn-2.00Ag) diffusion couple within the experimental temperature range. These findings offer valuable insights into factors affecting the reliability and performance of solder joints in electronic packaging applications.
- Published
- 2024
- Full Text
- View/download PDF
20. Quasi-in-situ observing unusual grain orientation rotation during the process of static recrystallization grain growth in Mg–Zn-Gd alloy
- Author
-
Lingyu Zhao, Zhenhua Wang, Hong Yan, Zhongtang Wang, Quan Liu, Boyu Liu, Zhiwei Shan, and Rongshi Chen
- Subjects
Orientation ,Rotation ,Grain growth ,Mg alloys ,Quasi-in-situ EBSD ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The orientation (including the c axis orientation and crystal direction parallel to rolling direction) evolution of grown recrystallization grains during annealing at 250 °C for 45–180 min in Mg–Zn-Gd alloy was characterized by quasi-in-situ electron backscatter diffraction method. An unusual grain orientation rotation during the process of static recrystallization grain growth, rather than common plastic deformation or recrystallization nucleation process, was observed. Due to the higher storage energy, the growth size in the early stage of annealing (1.41 μm) is larger than that in the late stage of annealing (0.73 μm) for most (∼76%) grains, and corresponding average c-axis rotation angles are 3.65° and 1.39°, respectively, indicating that the larger the increase in grain size, the greater the changing degree in grain orientation. It is speculated that the orientation rotation during grain growth process is mediated by the interaction between dislocations and grain boundaries. The results reported in the current paper can provide a new insight into the study on the relationship between preferential grain growth and non-basal texture formation in rare earth contained Mg alloys.
- Published
- 2024
- Full Text
- View/download PDF
21. Low temperature enhancement of densification in freeze-casted porous alumina upon the addition of TiO2
- Author
-
Jong-Won Woo, Sung-Hyun Kim, Sang-Min Hong, Jong-Won Kim, Kyoung-Seok Moon, Dong-Yeol Yang, and Sang-Chae Jeon
- Subjects
Porous materials ,Freeze-casting ,Alumina ,Densification ,Grain growth ,Mining engineering. Metallurgy ,TN1-997 - Abstract
Mechanical stability of freeze-casted porous alumina can be achieved by the stimulation of densification with control of the grain growth during sintering. To tailor the porous microstructure beneficially, in this study TiO2 was added and its segregation effect on the densification and its grain growth behaviors were investigated. As a result, abnormal grain growth was observed with faceted interfaces and explained by grain boundary structure dependent grain growth theory. In terms of densification, a higher bulk density was obtained with the addition of 1.5 wt% TiO2 (41.76 %TD) compared to that without doping (36.02 %TD). The benefit was evident at 1400 °C, whereas the bulk density decreased even with an addition of TiO2 above 1500 °C. This temperature dependence could be understood by a change in the dominant densification mechanism at 1500 °C, solving the puzzle of the enhanced densification only at low temperature.
- Published
- 2024
- Full Text
- View/download PDF
22. An in-situ study of static recrystallization in Mg using high temperature EBSD
- Author
-
Xu Ye, Zhe Suo, Zhonghao Heng, Biao Chen, Qiuming Wei, Junko Umeda, Katsuyoshi Kondoh, and Jianghua Shen
- Subjects
Pure Mg ,In-situ ,HT-EBSD ,Recrystallization ,Grain growth ,Mining engineering. Metallurgy ,TN1-997 - Abstract
It has been a common method to improve the mechanical properties of metals by manipulating their microstructures via static recrystallization, i.e., through heat treatment. Therefore, the knowledge of recrystallization and grain growth is critical to the success of the technique. In the present work, by using in-situ high temperature EBSD, the mechanisms that control recrystallization and grain growth of an extruded pure Mg were studied. The experimental results revealed that the grains of priority for dynamic recrystallization exhibit fading competitiveness under static recrystallization. It is also found that grain boundary movement or grain growth is likely to show an inverse energy gradient effect, i.e., low energy grains tend to swallow or grow into high energy grains, and grain boundaries of close to 30° exhibit superior growth advantage to others. Another finding is that {10–12} tensile twin boundaries are sites of hardly observed for recrystallization, and are finally swallowed by adjacent recrystallized grains. The above findings may give comprehensive insights of static recrystallization and grain growth of Mg, and may guide the design of advanced materials processing in microstructural engineering.
- Published
- 2024
- Full Text
- View/download PDF
23. Mechanical properties of Ce-TZP/Al2O3 ceramic composites as a function of sintering parameters
- Author
-
B. X. Freitas, E. T. Duarte, J. E. A. Vasconcelos, R. O. Magnago, K. Strecker, and C. Santos
- Subjects
Ce-TZP/Al2O3/H6A composites ,densification ,grain growth ,mechanical properties ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Abstract Ceramic composites based on Ce-TZP/Al2O3/H6A were sintered in order to promote grain growth and to study the effects of ZrO2 grain size on the properties of this material. A mixture of ZrO2-CeO2-Al2O3 powders was sintered at 1450 °C-2 h, following the manufacturer’s recommendations. Then, the samples were further treated at 1500 or 1600 °C, for 0, 2, 8, or 24 h. The sintered specimens were characterized by X-ray diffraction, relative density, and grain size distribution. Vickers nanohardness, Young’s modulus (E), and fracture toughness were measured. The materials showed complete densification for all sintering conditions studied. t-ZrO2, α-Al2O3, and cerium hexaluminate (H6A) were observed. The alumina and hexaluminate grains had average grain sizes of 0.7 and 4.5 μm (AR>3), respectively, without significant variations during the additional heat treatments. However, significant growth took place for the ZrO2 grains with increasing temperature and holding time, increasing the average grain size from 0.6~1.4 μm, when sintered at 1500 °C-2 h to 1600 °C-24 h, respectively. The materials exhibited Vickers nanohardness of 1800 HV and E=241±15 GPa. On the other hand, the considerable grain growth of the ZrO2 grains as a function of holding time reflected in a reduction of the fracture toughness, which decreased from 8.5 to 5.7 MPa.m1/2 for samples sintered at 1500 °C-2 h to 1600 °C-24 h, respectively.
- Published
- 2024
- Full Text
- View/download PDF
24. Texture-Differentiated Grain Growth in Silicon Steel: Experiments and Modeling.
- Author
-
Chang, Songtao, Sha, Yuhui, Cao, Gengsheng, Zhang, Fang, and Zuo, Liang
- Subjects
- *
SILICON steel , *PARTICLE size distribution , *GRAIN , *SPATIAL arrangement - Abstract
Grain growth for various texture components in silicon steel was investigated via experiments and modeling. It was found that the clustered spatial arrangement of grains with specific orientations significantly altered the local environment for grain growth and consequently resulted in texture-differentiated grain size distribution (GSD) evolution. A novel local-field model was proposed to describe grain growth driven by continuous changing orientation and size distribution of adjacent grains. The modelling results show that the texture-differentiated grain growth in microstructure with grain clusters can produce a GSD with increased proportion in small-sized range and large-sized range by more than two-times, accompanied with an evident change in area fractions of various texture components. The effect of clustered spatial arrangement on grain growth can be precisely predicted, which is valuable to design and control the texture-differentiated GSD as well as the global GSD. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. Large-scale synthesis of size-controlled amorphous and anatase TiO2 via a benzoic acid-assisted sol-gel-hydrothermal process.
- Author
-
Wu, Hao, Qin, Pinquan, Cao, Shaowen, Luo, Guoqiang, Wang, Chuanbin, Tu, Rong, Shen, Qiang, and Zhang, Lianmeng
- Subjects
- *
TITANIUM dioxide , *TITANIUM dioxide nanoparticles , *BENZOIC acid , *SOL-gel processes - Abstract
The ability to control the particle size of titanium dioxide nanoparticles (TNPs) is crucial for their practical use. This study presents a method for preparing monodisperse amorphous and anatase TNPs with high surface areas and tunable grain sizes. The method combines a sol-gel process with a hydrothermal process, using benzoic acid (BA) as a structure-directing agent. By adjusting the hydrolysis and condensation rates of the titanium alkoxide, we can synthesize monodisperse amorphous TNPs with a controllable size range of 200–800 nm. Additionally, the amorphous TNPs synthesized through this method serve as raw material, enabling the morphology of anatase TNPs to be inherited from amorphous TNPs with a hydrothermal reaction time of 1 h. When the hydrothermal reaction time is extended to 10 h, the closely linked primary titanium dioxide is fully separated and replaced by ultra-fine anatase TNPs. This optimal scheme show promise for self-assembly and large-scale synthesis of monodisperse amorphous and anatase TNPs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. A novel class of ATF fuels with large grain size, enhanced thermophysical properties and oxidation resistance.
- Author
-
Yang, Zhenliang, Li, Bingqing, Xu, Jingkun, Zhong, Yi, Xie, Liang, Chu, Mingfu, Wang, Yun, Gao, Rui, Yu, Libing, Wang, Mingshan, Zhao, Guoliang, Zhang, Pengcheng, Bai, Bin, and Xu, Chen
- Subjects
- *
GRAIN size , *THERMOPHYSICAL properties , *THERMAL conductivity , *THERMAL expansion , *OXIDATION , *METALLIC composites - Abstract
Two strategies have been extensively employed to develop advanced accident tolerant fuels (ATF): improving thermal conductivity and producing large grain sized pellets. However, there are few reports on the simultaneous utilization of both strategies. In this work, we fabricated Mo–Cr alloy reinforced UO 2 (UMC) composite pellet with both high thermal conductivity and large grain size by a simple in-situ alloying method for the first time. The average grain size of UO 2 increased from 6 μm to 113 μm. Thermal conductivity of the UMC pellet (with 2 vol% Mo) at 1200 °C increased by 36.46% compared with pure UO 2. The increase rate of thermal conductivity per 1 vol% dopant reached about 18%. The Mo–Cr alloy formed continuous micro-cell layer around UO 2 particles. Such continuous micro-cell Mo–Cr alloy layer and increase of UO 2 grain size both helped improve the thermal conductivity of UMC composite pellets. Thermal expansion coefficient of the UMC under the operating temperature decreased by 11.90% compared with pure UO 2. The oxidation resistance of the UMC pellet under high temperature steam was also improved. This work provides a new strategy towards fabricating ATF with both high thermal conductivity and large grain size. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Corrosion behavior of cold rolled and continuously heated SUS 304L stainless steel.
- Author
-
Sohrabi, Mohammad Javad, Dehghanian, Changiz, and Mirzadeh, Hamed
- Subjects
STAINLESS steel ,CORROSION resistance ,GRAIN refinement ,X-ray diffraction ,HIGH temperatures - Abstract
The effect of continuous heating after cold deformation on the microstructural evolutions and corrosion behavior of SUS 304L metastable austenitic stainless steel was investigated. After cold rolling with the reduction in thickness of 80%, a microstructure consisting of elongated grains was obtained, in which the X-ray diffraction (XRD) analysis revealed the formation of 96 vol.% strain-induced martensite. The subsequent continuous heating up to 750 °C led to full reversion/recrystallization and the development of an ultrafine grained (UFG) microstructure with an average grain size of 0.45 µm. Continuous heating up to higher temperatures resulted in a significant grain growth, where the average grain size of samples that heated up to 850, 900, 950, and 1100 °C were obtained as 2.5 µm, 5.5 µm, 14 µm, and 45 µm, respectively. The Hall-Patch relationship of H = 155 + 106/√D was developed for the dependence of hardness on the average grain size (D). By grain refinement, corrosion current density (i
Corr ) increased leading to the worsening of uniform corrosion resistance. However, breakdown potential (EBr ) increased by grain refinement, indicating the improved pitting resistance. The Hall-patch-type equations of iCorr = 0.0147 + 0.4458/√D and EBr = 0.1964 + 0.0695/√D were proposed for correlating the corrosion parameters to D. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
28. Computationally Efficient Algorithm for Modeling Grain Growth Using Hillert's Mean-Field Approach.
- Author
-
Chatroudi, Shabnam Fadaei, Cicoria, Robert, and Zurob, Hatem S.
- Subjects
- *
MANUFACTURING processes , *ALGORITHMS , *HOT rolling , *ANALYTICAL solutions - Abstract
To investigate the interconnected effects of manufacturing processes on microstructure evolution during hot-rolling, a through process model is required. A novel numerical implementation of the mean-field approach was introduced to efficiently describe the grain growth of larger systems and extended durations. In this approach, each grain is embedded within an average medium and interacts with the average medium, thus avoiding the complexities of individual grain interactions. The proposed upsampling approach dynamically adjusts the simulation grain ensemble, ensuring efficiency and accuracy regardless of the initial number of grains present. This adaptation prevents undersampling artifacts during grain growth. The accuracy of the model is verified against analytical solutions and experimental data, demonstrating high agreement. Moreover, the effects of different initial conditions are successfully investigated, demonstrating the model's versatility. Due to its simplicity and efficiency, the model can be seamlessly integrated into other microstructure evolution models. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Enhanced Copper Bonding Interfaces by Quenching to Form Wrinkled Surfaces.
- Author
-
Lu, Tsan-Feng, Yen, Yu-Ting, Wang, Pei-Wen, Cheng, Yuan-Fu, Chen, Cheng-Hsiang, and Wu, YewChung Sermon
- Subjects
- *
THREE-dimensional integrated circuits , *MOORE'S law , *STRAIN energy , *COPPER , *SURFACE morphology , *SUBSTRATES (Materials science) , *SURFACE preparation , *SOLDER & soldering - Abstract
For decades, Moore's Law has been approaching its limits, posing a huge challenge for further downsizing to nanometer dimensions. A promising avenue to replace Moore's Law lies in three-dimensional integrated circuits, where Cu–Cu bonding plays a critical role. However, the atomic diffusion rate is notably low at temperatures below 300 °C, resulting in a distinct weak bonding interface, which leads to reliability issues. In this study, a quenching treatment of the Cu film surface was investigated. During the quenching treatment, strain energy was induced due to the variation in thermal expansion coefficients between the Si substrate and the Cu film, resulting in a wrinkled surface morphology on the Cu film. Grain growth was observed at the Cu–Cu bonding interface following bonding at 300 °C for 2 and 4 h. Remarkably, these procedures effectively eliminated the bonding interface. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Effect of laser wavelength on the thermoelectric properties of Bi1.6Pb0.4Sr2Co2O8 textured ceramics processed by LFZ.
- Author
-
Amirkhizi, P., Madre, M.A., Dura, O.J., Torres, M.A., Sotelo, A., Kovalevsky, A., and Rasekh, Sh.
- Subjects
- *
THERMOELECTRIC materials , *SEEBECK coefficient , *CARBON dioxide , *ND-YAG lasers , *CERAMICS , *LASER beams , *THERMAL conductivity , *PHONON scattering - Abstract
Bi 1.6 Pb 0.4 Sr 2 Co 2 O 8 samples have been textured by the Laser Floating Zone (LFZ) process using Nd:YAG, and CO 2 laser radiation. Using different wavelengths resulted in significant structural and microstructural modifications. Powder XRD patterns showed that the thermoelectric phase is the major one in both cases. Microstructural studies revealed that all samples presented the same phases but with much lower content of secondary ones in those processed with the CO 2 laser. Electrical resistivity showed different behavior for the two types of samples, being in general, lower for the CO 2 grown rods. Seebeck coefficient is lower for the CO 2 grown samples up to 300 °C, and higher in the high-temperature range, reaching 240 μV/K at 650 °C, which is one of the highest values obtained so far in these compounds. Moreover, thermal conductivity at 600 °C for these samples (0.93 W/K m) is among the lowest reported in the literature. As a consequence, ZT values at 600 °C reached 0.42 in CO 2 textured materials, about two times higher than the obtained in Nd:YAG ones. This value is among the highest reported so far in the literature, and is comparable to the performance attained for the same composition containing nanoparticles addition. All these properties, combined with the fact that the processed materials can be directly integrated into thermoelectric modules, render them highly attractive for industrial production. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Microstrain effect of single crystalline LiNi0.7Co0.1Mn0.2O2 cathode material on Ni0.7Co0.1Mn0.2(OH)2 precursor stacking.
- Author
-
Xue, Lingfeng, Tian, Changhao, Liu, Yite, Wen, Xue, Huang, Tao, and Yu, Aishui
- Subjects
- *
CRYSTAL lattices , *CATHODES , *ANISOTROPIC crystals , *ENERGY density , *SURFACE area , *ELASTIC modulus - Abstract
LiNi x Co y Mn 1-x-y O 2 (NCM) has been regarded as promising cathode materials for high energy density lithium ion battery. Apart from the capacity deterioration during cycling process, NCM particle microcracks' generation resulting from anisotropic strain in crystal lattice is also regarded as the crucial issue from mechanical scale. As the original materials of synthesizing NCM, NCMOH precursor decides much of the prepared NCM materials in both electrochemical and mechanical scale while mechanical degrading mechanism inside crystal lattice is missing in related literature. In this study, the LiNi 0.7 Co 0.1 Mn 0.2 O 2 single crystalline particles are calcined from NCMOH precursors with difference in mechanical stacking morphology and physical property (specific surface area and tapping density) through the same appropriate sintering condition. The evolution of lattice microstrain calculation and elastic modulus for NCM materials through structure and mechanical evaluation has been studied. It is indicated that larger size and higher rate capability (fast charging) of single crystalline LNCMO materials can be obtained from precursor with smaller specific surface area and higher tapping density while the larger microstrain and less elastic modulus degradation are determined during electrochemical charging process. Stronger structure maintaining ability of NCM lattice under large electric field force (during fast charging process) is beneficial to the capacity performance related with higher-rate capability. This might provide a novel insight of understanding the mechanical effect of NCMOH precursors on the synthesis and electrochemical performance of Ni-rich LiNi x Co y Mn 1-x-y materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. A Common Diffusional Mechanism for Creep and Grain Growth in Polymineralic Rocks: Application to Lower Mantle Viscosity Estimates.
- Author
-
Okamoto, A. and Hiraga, T.
- Subjects
- *
ROCK creep , *VISCOSITY , *PHASE transitions , *LATERAL loads , *STOKES flow , *CREEP (Materials) , *GRAIN size , *FREE convection - Abstract
In a previous study (Okamoto & Hiraga, 2022, https://doi.org/10.1029/2022jb024638), we concluded that diffusion creep and grain growth in polymineralic rocks proceed by a common diffusional mechanism. Here, we built on that finding and estimated lower mantle grain size and viscosity during a single mantle convection cycle dominated by diffusion creep. We approximated the lower mantle as a two‐phase material consisting of bridgmanite + ferropericlase and post‐perovskite + ferropericlase, depending on depth. We used previously reported self‐diffusivities for bridgmanite and post‐perovskite. We predict a bridgmanite grain‐size of tens to hundreds of microns shortly after the phase transition at ∼660 km depth. This size remains relatively constant until the mantle material enters the post‐perovskite zone, which is marked by significant grain growth up to ∼9 mm just prior to upwelling. This size is sufficient to prevent further grain growth until the mantle material reaches the top of the lower mantle. These grain sizes combined with the diffusivities yield viscosities that vary laterally and with depth. At a lateral temperature difference of up to 800 K in the lower mantle, fine‐grained cold downwelling mantle is almost as viscous as, or more likely to be softer than coarse‐grained hot upwelling mantle. The lateral viscosity variations cannot be more than 2 orders of magnitude, and we estimated viscosities of 1018–1020 Pa · s in the upper lower mantle, 5 × 1020–5 × 1022 Pa · s in the lower bridgmanite zone, and 1017–1019 Pa · s in the post‐perovskite zone, which compare well with the values estimated in previous geophysical modeling studies. Plain Language Summary: We estimated lower mantle viscosity during a mantle convection cycle by assuming that the mantle flows by diffusion creep. Because diffusion creep is a grain‐size sensitive mechanism, grain size is a key parameter for determining mantle viscosity. We recently concluded that diffusion creep and grain growth in polymineralic rocks occur by the same diffusional mechanism. With previously reported self‐diffusivities for bridgmanite and post‐perovskite, we were able to estimate how the grain size of these minerals evolves after the ∼660‐km phase transition in downwelling mantle. Using these grain sizes and diffusivities, we were able to determine the mantle viscosity. We demonstrate that lower mantle viscosity has temporal and spatial variations induced by grain growth. At a lateral temperature difference of up to 800 K in the lower mantle, fine‐grained cold downwelling mantle is almost as viscous as, or more likely to be softer than coarse‐grained hot upwelling mantle. The estimated overall viscosity structure compares well with a one‐dimensional depth structure of the lower mantle viscosity estimated in previous geophysical modeling studies. Key Points: We estimated lower mantle viscosity during a mantle convection cycle by assuming mantle flow with a diffusion creep mechanismOur estimated viscosity structure agrees well with the viscosity structures predicted in previous geophysical modelsTemperature and grain size dependence of diffusion creep suppresses lateral changes in the viscosity of the lower mantle [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. Separative and Comprehensive Effects of Grain Coarsening and Grain Refinement of Ni-38Cr-3.8Al Alloy during Thermal Deformation Process.
- Author
-
Quan, Guozheng, Zhao, Yifan, Deng, Qi, Quan, Mingguo, Yu, Yanze, and Wu, Daijian
- Subjects
- *
GRAIN refinement , *ISOTHERMAL compression , *GRAIN , *STRAIN rate , *ALLOYS , *TEMPERATURE effect - Abstract
During thermal deformation, grain coarsening due to grain growth and grain refinement resulting from dynamic recrystallization (DRX) collectively influence the deformed grain size. To investigate the separative and comprehensive effects of the two mechanisms in the Ni-38Cr-3.8Al alloy, grain growth experiments and isothermal compression tests were conducted. Kinetics models for grain growth and DRX behaviors were established based on the experimental data, which were integrated with finite element (FE) techniques to simulate the evolution of grain size throughout the entire thermal compression process. The effects of grain coarsening and grain refinement during this process were separated and quantified based on the simulation data. The results revealed that grain coarsening predominated during the heating and holding stages, with a longer holding time and higher holding temperatures intensifying this effect. However, during the compression stage, grain coarsening and grain refinement co-existed, and their competition was influenced by deformation parameters. Specifically, grain refinement dominated at strain rates exceeding 0.1 s−1, while grain coarsening dominated at lower strain rates (<0.1 s−1) and higher deformation temperatures (>1373 K). The simulated grain sizes closely matched the experimental observations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Promoting effects of alternating current and input power on grain growth behavior of cubic ZrO2 polycrystals.
- Author
-
Nambu, Kohta, Ishii, Akio, Soga, Kohei, and Morita, Koji
- Subjects
- *
POINT defects , *POLYCRYSTALS , *THERMAL diffusivity , *POWER density , *ELECTRIC currents , *CRYSTAL grain boundaries , *HEAT treatment - Abstract
The grain growth behavior during an AC flash event was examined in 8 mol% yttria‐stabilized cubic zirconia (8Y‐CSZ) polycrystals. The effects of current/power densities on the grain growth behavior were investigated in 8Y‐CSZ samples with different specific surface areas at a constant sample temperature and applied field strength. The grain growth rate of flash‐treated 8Y‐CSZ was 300 times faster than that of heat‐treated 8Y‐CSZ at the same sample temperature in the absence of an electric current/field, suggesting that the promoted grain growth cannot be ascribed only to a thermal effect but also to an athermal effect occurring during the AC flash event. Moreover, the grain growth during the flash treatment strongly depends on the applied current/power densities and grain size; in particular, the grain growth showed enhancements with increasing applied current/power densities and for relatively small grain sizes. This result suggests that the grain boundary diffusivity of cations, which are regarded as the rate‐controlling species for grain growth, could be accelerated by tuning the current/power densities during the flash event. The grain growth mechanism was characterized using a grain growth exponent (n) value of 4.8 for the flash treatment at high current/power densities and using a conventional value of n = 3 under normal heat treatment conditions. The dependence of the grain growth behavior on the AC current/power density suggests that because the cation diffusivity is accelerated due to the formation of numerous point defects during the AC flash event, the grain growth mechanism might depend on the current/power densities and differ from that of conventional grain growth. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
35. Enhanced compressive strength of porous alumina realized by synergy between La‐doping and two‐step sintering.
- Author
-
Kim, Sung‐Hyun, Woo, Jong‐Won, Hong, Sang‐Min, Kim, Jong‐Won, Moon, Kyoung‐Seok, Yang, Dong‐Yeol, and Jeon, Sang‐Chae
- Subjects
- *
COMPRESSIVE strength , *SINTERING , *SPECIFIC gravity , *MANUFACTURING processes , *GRAIN size - Abstract
Sintering phenomena, densification, and grain growth are crucial for proper control of the microstructure for good mechanical strength. Here, materials and processing parameters, the addition of La2O3, and two‐step sintering (TSS) were combined to lead to higher strength in the porous alumina prepared by freeze‐casting. Based on grain growth and densification behaviors with the La2O3 doping, a beneficial thermal profile was designed for the TSS. As a result, higher relative density levels and smaller grain size were obtained compared with the results with conventional sintering (CS): 38.56% and 0.82 µm at 1500°C by CS; 40.78% and 1.78 µm at 1600°C by CS; 41.43% and 0.87 µm by TSS. The microstructural benefits provided ∼1.4 times higher compressive strength (5.46 MPa) from TSS than from the CS sample (3.92 MPa), highlighting the synergetic effect of La2O3 doping and the TSS strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. A mathematical model for the prediction of mechanical properties on ASTM A510/A853 cold-drawn hypoeutectoid steel wire after batch annealing.
- Author
-
Sánchez de León, José Alfredo
- Subjects
- *
STEEL wire , *MECHANICAL models , *PREDICTION models , *MATHEMATICAL models , *WIREDRAWING , *WIRE - Abstract
Annealed ASTM A510/A853 hypoeutectoid steel wire is a very useful and versatile material that finds its applications in the construction industry; this is mainly due to its mechanical properties, since this product can reach high ductility. In order to achieve the sought quality and homogeneity in this material, it is necessary to have a suitable control during operation. Important operational control parameters in batch annealing are: heating and cooling rates, holding temperature and cycle time. These parameters have a direct effect on the process, and it is essential to elucidate the way they impact in the final product. This work concerns the development of a mathematical model targeted at the prediction of mechanical properties in terms of the operational parameters, in the outer spirals of American Iron and Steel Institute/Society of Automotive Engineers (AISI/SAE) steel drawn wire coils after they have been subjected to batch annealing. The model addresses non-isothermically the involved phenomena that take place during the annealing process: recovery, recrystallization, and grain growth below and above Ac1. It predicts grain size, tensile strength, and yield strength values with very good accuracy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Kinetics of microwave carbothermal reduction of Sb2O3: Isothermal and non‐isothermal microwave thermogravimetric analysis.
- Author
-
Yang, Qinsheng, Liu, Chenhui, Zhu, Xiongjin, Srinivasakannan, Chandrasekhar, Li, Yingwei, and Dai, Ying
- Subjects
- *
THERMOGRAVIMETRY , *MICROWAVES , *MICROWAVE heating , *ACTIVATION energy , *ANTIMONY , *SURFACE diffusion , *OXYGEN reduction - Abstract
Kinetics of antimony production via carbothermal reduction of Sb2O3–carbon powder–NaCl mixture using microwave and conventional heating was investigated to identify the dominant controlling mechanism. Results of conventional heating revealed the temperature range of conventional carbothermal reduction reaction is 500°C to 800°C, with the average activation energy of each stage being 81.97 kJ/mol (α = 0.1–0.5), 65.17 kJ/mol (α = 0.5–0.75), and 69.86 kJ/mol (α = 0.75–1.0), respectively. In the microwave field, the carbothermal reduction reaction of raw materials can be completed at 600°C to obtain antimony, and the weight loss data of the carbothermal reduction process were recorded for the first time. The above results show that the microwave field enhanced the interfacial chemical effect, accelerated the interfacial diffusion from the metal phase to the oxide phase, and reduced the activation energy of the carbon thermal reduction process to 6.85 kJ/mol. The growth index of antimony grain growth process is estimated to be 4.33, controlled by the surface diffusion. These data provide a reliable theoretical basis for studying the reduction reactions of minerals in microwave fields. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Large-Scale Multi-Phase-Field Simulation of 2D Subgrain Growth.
- Author
-
Khajezade, Ali, Poole, Warren J., Greenwood, Michael, and Militzer, Matthias
- Subjects
RECRYSTALLIZATION (Metallurgy) ,MICROSTRUCTURE - Abstract
The characteristics of subgrains in a deformed state after the high-temperature deformation of aluminum alloys control the subsequent recrystallization process and corresponding mechanical properties. In this study, systematic 2D phase-field simulations have been conducted to determine the role of deformed state parameters such as subgrain size and disorientation distributions on subgrain growth in an individual grain representing a single crystallographic orientation. The initial subgrain size and disorientation distributions have been varied by ±50%. To have a statistically relevant number of subgrains, large-scale simulations have been conducted using an in-house-developed phase-field code that takes advantage of distributed computing. The results of these simulations indicate that the growth of subgrains reaches a self-similar regime regardless of the initial subgrain structure. A narrower initial subgrain size distribution leads to faster growth rates, but it is the initial disorientation distribution that has a larger impact on the growth of subgrains. The results are discussed in terms of the evolution of the average diameter of subgrains and the average disorientation in the microstructure. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Simulation of the Growth of an Ensemble of Austenite Grains Considering the Inhibition by Particles of the Second Phases.
- Author
-
Gorbachev, I. I.
- Subjects
AUSTENITE ,ALLOYS ,STEEL ,GRAIN - Abstract
Methods to simulate the grain growth in alloys considering the inhibition of this growth by second-phase particles have been proposed. The presented approaches are primarily focused on low-alloyed steels with carbonitride strengthening. The calculation results have been compared with the experimental data available in the literature and their satisfactory agreement has been shown. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. The influence of Mo addition on static recrystallization and grain growth behaviour in CoNiFeMn system subjected to prior deformation.
- Author
-
Cichocki, K., Bala, P., Kwiecien, M., Szymula, M., Chrzan, K., Hamilton, C., and Muszka, K.
- Subjects
- *
RECRYSTALLIZATION (Metallurgy) , *ENERGY dispersive X-ray spectroscopy , *COLD rolling , *HEAT treatment - Abstract
In this work, the influence of Mo in the CoNiFeMn system during heat treatment after prior hot and cold rolling was investigated. At present, relatively few studies on static recrystallization and grain growth kinetics in high entropy alloys are available. This paper focuses on static recrystallization and grain growth kinetics as well as the influence of molybdenum on these phenomena. This work compares two alloys, CoNiFeMn and (CoNiFeMn)95Mo5, in relation to the formations of the brittle µ phase at room- and high-temperature plastic deformation regimes due to its negative affect on material ductility. Microstructures were characterized by energy dispersive X-ray spectroscopy analysis and by scanning electron microscopy, whereas the mechanical properties were assessed by tensile testing. The effect of recrystallization and grain growth behaviours on the microstructural evolution and the final mechanical properties was assessed. It was found that Mo addition into the CoNiFeMn system has a strong effect on both the static recrystallization and grain growth kinetics as well as the final mechanical properties. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. An in-situ study of static recrystallization in Mg using high temperature EBSD.
- Author
-
Ye, Xu, Suo, Zhe, Heng, Zhonghao, Chen, Biao, Wei, Qiuming, Umeda, Junko, Kondoh, Katsuyoshi, and Shen, Jianghua
- Subjects
RECRYSTALLIZATION (Metallurgy) ,TWIN boundaries ,MECHANICAL properties of metals ,HIGH temperatures ,METAL microstructure ,CRYSTAL grain boundaries - Abstract
It has been a common method to improve the mechanical properties of metals by manipulating their microstructures via static recrystallization, i.e., through heat treatment. Therefore, the knowledge of recrystallization and grain growth is critical to the success of the technique. In the present work, by using in-situ high temperature EBSD, the mechanisms that control recrystallization and grain growth of an extruded pure Mg were studied. The experimental results revealed that the grains of priority for dynamic recrystallization exhibit fading competitiveness under static recrystallization. It is also found that grain boundary movement or grain growth is likely to show an inverse energy gradient effect, i.e., low energy grains tend to swallow or grow into high energy grains, and grain boundaries of close to 30° exhibit superior growth advantage to others. Another finding is that {10–12} tensile twin boundaries are sites of hardly observed for recrystallization, and are finally swallowed by adjacent recrystallized grains. The above findings may give comprehensive insights of static recrystallization and grain growth of Mg, and may guide the design of advanced materials processing in microstructural engineering. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. The Impact of Grain Growth on the Functional Properties in Room-Temperature Powder Aerosol Deposited Free-Standing (Ba,Ca)(Zr,Ti)O 3 Thick Films.
- Author
-
Maier, Juliana G., Fuggerer, Tim, Urushihara, Daisuke, Martin, Alexander, Khansur, Neamul H., Kakimoto, Ken-ichi, and Webber, Kyle G.
- Subjects
THICK films ,SCANNING transmission electron microscopy ,AEROSOLS ,TITANIUM powder ,RELAXOR ferroelectrics ,RESIDUAL stresses ,POWDERS - Abstract
This study investigates the development of freestanding thick films (FSFs) of lead-free (Ba,Ca)(Zr,Ti)O
3 and the role of grain growth on the electromechanical response. During deposition, room temperature powder aerosol deposition rapidly produces thick films with a nano-grain structure that limits the electromechanical properties. In this study, the films are removed from the substrate using a sacrificial buffering layer to avoid thermal treatment and allow for an initial as-processed state. Following this, FSFs were thermally treated at various annealing temperatures from 800 °C to 1400 °C to induce grain growth, which was characterized with scanning and transmission electron microscopy. X-ray diffraction revealed an increase in the crystallite size consistent with an increase in grain size and a decrease in internal residual stress. The temperature-dependent dielectric behavior and the large-field ferroelectric response were also characterized, revealing significant differences of the FSFs from the bulk properties. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
43. Wear behaviour of Al-MWCNT composites by varying MWCNTs concentration
- Author
-
Rahul Sharma, C. Sasikumar, and Jayashree Baral
- Subjects
Al-MWCNT ,Light weight composites ,Mechanical alloying ,Sintering ,Grain growth ,Hardness ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The present study illustrates the mechanical and wear behaviour of Al-MWCNT composites by varying MWCNTs concentration (0 %,0.25 %, 0.50 % & 1 %) by weight in composites. These composites were synthesized through sintering in the muffle furnace after mechanical alloying which involved flattening and welding particles to form flake-shaped lamellar particles. The presence of MWCNT lamellas restricted grain growth, creating a 2D aluminium layer between the MWCNTs during sintering. Increasing the MWCNT content in aluminum refined the interlayer thickness of the composites. The compressive strength of Al is increased exponentially with the addition of CNTs. By adding CNTs to aluminium, the maximum strength was reached at 460 MPa in 1% samples, and the compression strength of the aluminium increased by 84 % as well. The sintered composites exhibited higher hardness and its value increased significantly when CNTs were added to the Al composite. The wear resistance of aluminium is substantially increased when CNTs are added, and the maximum wear resistance is achieved when CNTs are added at 0.5 wt%. The addition of CNTs reduced wear resistance, which could be attributed to the decrease in interface adhesion and agglomeration effects of CNTs.
- Published
- 2024
- Full Text
- View/download PDF
44. Rapid densification of nanocrystalline zirconia: Pressureless versus pressure-assisted spark plasma sintering
- Author
-
Andraž Kocjan, Nikhil Bhootpur, Aljaž Iveković, and Mirva Eriksson
- Subjects
Spark plasma sintering ,Rapid sintering ,YSZ ,Nanoceramics ,Microstructure ,Grain growth ,Clay industries. Ceramics. Glass ,TP785-869 - Abstract
Spark plasma sintering (SPS) is the most straightforward way to rapidly sinter nanoceramics, but the applied pressure prevents sintering of additively manufactured ceramics. Therefore, fast firing techniques such as “pressureless” SPS and ultra-fast high-temperature sintering, based on intense thermal radiation, are gaining interest. Here we compare pressure/current-assisted and pressureless SPS techniques for the rapid heating (∼300 °C/min, 5 min) of nanocrystalline zirconia with high sintering activity. The applied pressure and current indeed contributed to the lowestr temperatures needed for full densification of nanocrystalline zirconia, retaining very fine grain size, but also induced tetragonal phase transformations in the final sintering stages. When the radiative heat transfer was “decoupled” (pressureless SPS), a pronounced temperature difference between graphite crucible wall and simulated specimen temperature along with non-steady-state conditions during dwell were observed. Nevertheless, high heating rates facilitated fine and dense microstructures even in the absence of pressure/current.
- Published
- 2024
- Full Text
- View/download PDF
45. Effect of powder composition, PTAW parameters on dilution, microstructure and hardness of Ni–Cr–Si–B alloy deposition: Experimental investigation and prediction using machine learning technique
- Author
-
Venkatesh Chenrayan, Kiran Shahapurkar, Chandru Manivannan, L. Rajeshkumar, N. Sivakumar, R. Rajesh sharma, and R. Venkatesan
- Subjects
Chromium boride ,Dilution ,Grain growth ,Heat affected zone ,GRA ,Machine learning ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
The implementation of hard-facing alloy on the existing materials caters the need for high-performance surfaces in terms of wear and high temperatures. The present research explore the effect of Plasma Transferred Arc Welding (PTAW) parameters and powder composition on dilution, microstructure and hardness of the commonly used hard-facing alloy Ni–Cr–Si–B powder. The hard-facing alloy was deposited with three weight proportions of boron (2.5 %, 3 % and 3.5 %). The statistical-based Grey Relational Analysis (GRA) followed by a Machine Learning Algorithm (MLA) was implemented to identify the ideal parameters and degree of significance of each parameter and for the prediction of the responses. The dilution percentage, microstructure analysis, and phase detection were estimated through elemental analysis, Scanning electron Microscopy (SEM) and X-ray Diffraction Analysis (XRD) respectively. The experimental and modelling results revealed that 400 mm/min of scanning speed, 8 gm/min of powder delivery, 14 mm of stand-off distance, and 120 A of current were the optimal parameters along with 3.5 wt% of boron powder composition to yield a better dilution, microstructure and hardness.
- Published
- 2024
- Full Text
- View/download PDF
46. Correlation study of self-annealing-induced recrystallization and grain growth mechanism in copper foil
- Author
-
Junqing Han, Yuying Wu, and Xiangfa Liu
- Subjects
Copper foil ,Recrystallization ,Self-annealing ,Grain growth ,Strength ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Copper foils demonstrate a tendency for self-annealing, which adversely impacts the stability of the products. The self-annealing induced recrystallization of copper foil is closely related to the grain growth mode. When copper foil grows in equiaxed grain mode, resulting in a decrease in tensile strength from 780 MPa to 330 MPa. Conversely, the columnar grain copper foil exhibits excellent room-temperature stability in mechanical properties. The mechanism of copper foil room temperature self-annealing behavior was put forward. It was found that the internal stress generated in the process of preparing copper foils is the key factor driving the recrystallization of equiaxed grains. This internal stress originates from nanocrystals and high-density dislocations, with the latter arising from the doping of organic elements. The initial high stress values and the plasticity of dislocations contributed to a noteworthy decrease in residual stress. As dislocation plasticity ensues, the anchoring of interstitial atoms gives rise to dislocation loops. The interaction between dislocation loops and coincident twin boundaries induces the formation of twin steps. The quantity of twins of equiaxed copper foil increases greatly after self-annealing. Conversely, the initial dislocation density of columnar grain copper foil is an order of magnitude lower than that of equiaxed grains.
- Published
- 2024
- Full Text
- View/download PDF
47. All-Cobalt-Free Layered/Olivine Mixed Cathode Material for High-Electrode Density and Enhanced Cycle-Life Performance
- Author
-
Kim, Chang-Su, Kim, Kookhan, Im, An-Seop, Kim, Sung-Su, Kim, Jongmin, and Eom, Ji-Yong
- Published
- 2024
- Full Text
- View/download PDF
48. Macrocrack propagation with grain growth on transient heat loaded tungsten
- Author
-
Roh, Ki-Baek, Lee, Myeong-Geon, Kim, Kyung-Min, and Kim, Gon-Ho
- Published
- 2024
- Full Text
- View/download PDF
49. Role of texture before rolling: a research based on texture and magnetic properties of 4.5 wt.% Si non-oriented electrical steel
- Author
-
Wang, Yu-fan, Zu, Guo-qing, Sun, Shi-cheng, Han, Ying, Zhu, Wei-wei, Wu, Hui, Zhao, Yu, and Ran, Xu
- Published
- 2024
- Full Text
- View/download PDF
50. Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms
- Author
-
H.T. Jeong, S.W. Lee, and W.J. Kim
- Subjects
Magnesium-lithium alloy ,Superplasticity ,Severe plastic deformation ,Grain size ,Grain growth ,Mining engineering. Metallurgy ,TN1-997 - Abstract
The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy (LAZ1011) with a grain size of 3.2 µm, primarily composed of the BCC β phase and a small amount of the HCP α phase, were examined in a temperature range of 473 K to 623 K. The microstructural refinement of this alloy was achieved by employing high-ratio differential speed rolling. The best superplasticity was achieved at 523 K and at strain rates of 10−4 -5 × 10−4 s−1, where tensile elongations of 550–600% were obtained. During the heating and holding stage of the tensile samples prior to tensile loading, a significant increase in grain size was observed at temperatures above 573 K. Therefore, it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and mechanisms. In the investigated strain rate range, the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding, while at high strain rates, lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation mechanism. It was concluded that solute drag creep is unlikely to occur. During the late stages of deformation at 523 K, it was observed that grain boundary sliding led to the agglomeration of the α phase, resulting in significant strain hardening. Deformation mechanism maps were constructed for β-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate, stress, temperature, and grain size, using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.
- Published
- 2024
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.