Search

The effects of heat treatment on the microstructure, mechanical properties and wear resistance of Selective Laser Melting Ti6Al4V alloy were systematically studied. The results show that the as-built part has an acicular α ′ martensite structure. The increase in heat treatment temperature causes the decomposition of acicular α ′ martensite, which leads to the decrease of the hardness of Ti6Al4V alloy. When the heat treatment temperature is 800∘C, the alloy forms an α ′ / α structure, which increases the tensile strength and elongation of the alloy by 12% and 23%, respectively. When the heat treatment reaches above 900∘C, the mechanical properties of the alloy decrease sharply due to the disappearance of the α ′ / α structure, the coarse grains of the α phase, and the increase of the content of the β phase. The tensile strength decreased from 935 MPa to 815 MPa, and the elongation decreased from 8.7% to 3.1%. With the increase of heat treatment temperature, the friction coefficient and wear rate increase linearly, which is opposite to the changing trend of hardness, and the wear mechanism is changed from single abrasive wear to abrasive wear and oxidative wear. This is attributed to the increase in the grain size of the alloy and the increase in the content of the β phase, resulting in a decrease in the overall hardness of the alloy. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the microstructural evolution, tensile characteristics, and strain-hardening response of AZ31B magnesium alloy welds as influenced by post-weld heat treatment (PWHT). Thus, the AZ31B alloy was welded by using a low-power pulsed Nd:YAG laser-arc hybrid welding equipped on the six-axis welding robot in the present study. Microstructure, mechanical properties and strain-hardening behaviors of the AZ31B joints under various post-weld heat treatment (PWHT) temperatures were characterized. As the heat treatment temperature increases, the grain size of the welded joint gradually increases, and the amount of β-Mg17AI12 phase noticeably decreases. The mechanical properties of the welded joint specimens showed a significant enhancement when subjected to heat treatment at 300 °C and 350 °C for 20 min. Especially, after 350 °C heat treatment for 20 min, the ultimate tensile strength (UTS) and elongation (EL) of specimen were 339.6 MPa and 20.1%, respectively, which were up to 99.5% and 98.5% of the AZ31B base material (BM). The strain-hardening capacity of specimens is significantly influenced by the grain size. Due to having the largest grain size, the 400–20 min specimen exhibited the highest hardening capacity and strain hardening exponent. In Kocks-Mecking type curves, both stage III and stage IV were observed in BM and joint specimens. At higher net flow stresses, the strain hardening rate in the 400–20 min joint specimen was higher due to the larger grains, which allowed for more dislocation accommodation and improved the capacity for dislocation storage. [ABSTRACT FROM AUTHOR]

Effects of heat treatment on the microstructure and performance of laser-welded joint for the novel heat-resistant aluminum alloy Al–12Ce–0.4Sc were studied. The results show that heat treatment has little effect on the tensile properties of welded joints at room temperature but exhibits a significant effect on the creep properties at high temperature of 300 ℃. The microhardness distribution in the fusion zone is uniform, with a value significantly higher than that of the aluminum base in the base material, but lower than that of the large blocky Al11Ce3 phase. Fractures occurred in the base material during the tensile tests at both room temperature and 300 ℃ high temperature for all joints. The elongation during the tensile test at 300 °C high temperature of the joint welded by cast base material (CA-LW) was approximately twice as high as that of the joint with post-heat treatment welded by cast base material (CA–LW–HT). The CA–LW–HT joint exhibited the best creep resistance with a steady-state creep rate of 3.2 × 10–8 s−1 at 300 ℃ and 55 MPa, which was two orders of magnitude lower than that of the CA–LW joint. A significant reduction in grain size and change in the form of the precipitated phases in the fusion zone were identified as the primary reasons for higher microhardness and strength in the fusion zone than in the base material. The grain size in the fusion zone was less than 1/10 of that in the base material, and large blocky primary Al11Ce3 in the base material almost completely disappeared after the welding process, as the microstructure transformed into eutectics of primary α-Al and nanoscale Al11Ce3/Al. Mild Sc enrichment observed at the Al11Ce3/Al matrix interface in the fusion zone significantly contributed to the maintenance of outstanding high-temperature performance in the fusion zone. [ABSTRACT FROM AUTHOR]

The effect of iso‐thermal heat treatments on powder bed fusion–laser beam (PBF–LB) AlSi10Mg alloy has been studied; however, an extensive process–property relationship evaluation has not yet been undertaken. In addition, the coarsening of eutectic Si from low‐to‐high (200–500 °C) temperature heat treatment has not been investigated systematically. Therefore, AlSi10Mg alloy is heat‐treated at 200, 300, 400, and 500 °C for holding times ranging from 0.5 to 32 h. Uniaxial tensile and hardness tests are conducted, and the microstructure is characterized. A unique approach is adopted for estimating Si solubility where 200 °C heat‐treated microstructure data to estimate solute trapping due to the high cooling rate in the as‐fabricated state. It is observed that increasing the heat‐treatment temperature and time reduces the strength and strain‐hardening rate but increases the tensile elongation up to 400 °C heat treatment. At 500 °C, the yield strength increases, and the elongation reduces compared with the 400 °C heat treatment owing to the refined Fe containing dispersoid formation at 500 °C. The important outcome of this study is heat‐treatment process–property contour maps that are useful for fine‐tuning the mechanical properties of PBF–LB AlSi10Mg alloy for industrial prototyping application. [ABSTRACT FROM AUTHOR]

Heat treatment is the critical step in achieving a refined microstructure and enhanced mechanical properties of TiAl-based alloys. This study investigated the influence of heat treatment temperature, cooling method, and heat treatment time on the microstructure and mechanical properties of an extruded powder metallurgy Ti-48Al alloy, and achieved the control of fully lamellar fine microstructures and the enhancement of performance through a simple heat treatment, rather than the traditional approach of homogenization followed by heat treatment. The results indicate that the heat treatment temperature determines the type of microstructure, while the cooling rate dictates the lamellar width. As the heat treatment temperature was increased from the two-phase region to the α single-phase region, the microstructure transitioned from duplex to near lamellar, and the alloy strength initially increased and then decreased, influenced by both the lamellar colony ratio and grain size. A rapid cooling rate (water quenching) induces a non-diffusive massive phase transformation, whereas a slow cooling rate (air cooling) gradually forms α2/γ lamellar colonies. Therefore, a suitable heat treatment regime for the powder metallurgy Ti-48Al alloy was determined to be 1340 °C/5 min/air cooling. The microstructure of the alloy was near lamellar, consisting of lamellar colonies approximately 50 μm and a small number of γ equiaxed grains of about 10 μm. Subsequently, the alloy exhibited a room temperature tensile strength of 784 MPa and a yield strength of 763 MPa, representing improvements of 17.0% and 38.7% over the extruded alloy, respectively. This research provides a reference for establishing a heat treatment process for powder metallurgy TiAl alloys. [ABSTRACT FROM AUTHOR]

Al0.6CoFeNi2V0.5 high entropy alloy was successfully designed and prepared via the nonconsumable arc-melting process, and it was annealed at 600 °C, 800 °C, and 1000 °C for 4 h. Its microstructure and mechanical properties were studied. The as-cast alloy consisted of FCC and BCC phases, and no phase transformation occurred during annealing at 600 °C. Hard Al3V-type metal compounds precipitated during annealing at 800 °C, and BCC particles precipitated in the FCC matrix during annealing at 1000 °C. After annealing, the strength and hardness of Al0.6CoFeNi2V0.5 high-entropy alloy both showed a decreasing trend, because the annealing process eliminated the internal stress in this alloy. However, as the annealing temperature increased, the strength and hardness of the Al0.6CoFeNi2V0.5 high-entropy alloy samples gradually increased. This is because the hard Al3V metal compounds precipitated when the annealing temperature was 800 °C, which produced the "second phase strengthening" effect. At 1000 °C, the larger volume fraction of the hard and fine BCC phase (21.81%) diffusely precipitated; the precipitation of this BCC phase not only produced a "second phase strengthening" effect, which also resulted in "solid solution strengthening", ultimately exhibiting enhanced hardness and strength. These findings have important theoretical reference value for the study of the microstructure and mechanical properties of high-entropy alloys. And, this study plays a significant role in promoting the research and development of new component materials that bear compressive loads, such as columns in large factory buildings, supports for cranes, and clamping bolts for rolling mills in practical mechanical engineering. [ABSTRACT FROM AUTHOR]

The effect of pre-weld heat treatment on the microstructure and low-temperature impact toughness of the coarse-grained heat-affected zone (CGHAZ) after simulated welding was systematically investigated through the utilization of scanning electron microscopy (SEM) and electron back-scattering diffraction (EBSD). The Charpy impact test validated the presence of an optimal pre-weld heat treatment condition, resulting in the highest impact toughness observed in the CGHAZ. Three temperatures for pre-weld heat treatment (690, 720 and 750 °C) were used to obtain three different matrices (Steel 1, Steel 2, Steel 3) for simulated welding. The optimal pre-weld heat treatment is 720 °C for 15 min followed by water quench. Microstructure characterization showed that there is an evident microstructure comprising bainite (B) in Steel 1 and Steel 2 after pre-weld heat treatment, while the addition of martensite (M) with the pre-weld heat treatment temperature exceeds Ac1 by almost 60 °C (Steel 3). These differences in microstructures obtained from pre-weld heat treatment influence the refinement of high-temperature austenite during subsequent simulated welding reheating processes, resulting in distinct microstructural characteristics in the CGHAZ. After the optimal pre-weld heat treatment, Steel 2 subjected to single-pass welding thermal simulation demonstrates a refined microstructure characterized by a high density of high-angle grain boundaries (HAGBs) within the CGHAZ, particularly evident in block boundaries. These boundaries effectively prevent the propagation of brittle cracks, thereby enhancing the impact toughness. [ABSTRACT FROM AUTHOR]

The tailored thermal heat-treatment process for Ti-6Al-4V alloy manufactured by laser–arc hybrid additive manufacturing can achieve desired microstructures and excellent mechanical properties for components. The effects of different heat treatment regimens on the microstructure and mechanical properties of Ti-6Al-4V alloy manufactured by laser–arc hybrid additive manufacturing are investigated in this study. Utilizing optical microscopy and scanning electron microscopy, we analyze the variations in microstructure with changes in heat-treatment parameters and explore the reasons for the changes in mechanical properties under different solutions' treatment temperatures and cooling rates. The microstructure of Ti-6Al-4V alloy fabricated via laser–arc hybrid additive manufacturing was primarily composed of Widmanstätten α plate structures and a small amount of acicular martensite α′ within columnar β grains that grew outward from the substrate along the deposition direction. Following solution treatment and aging heat treatment, the microstructure transitioned to a typical high-performance net basket structure with significantly reduced α plate thickness, leading to noticeable enhancements in sample ductility and toughness. Specifically, when the solution treatment and aging treatment regimen was set at 950 °C for 1 h, followed by air cooling, and then aging at 540 °C for 6 h with subsequent air cooling, the average grain size decreased by a factor of two compared to the as-deposited samples, while the impact toughness increased by 66.7%. [ABSTRACT FROM AUTHOR]

In this study, the effect of heat treatment on the microstructure and mechanical properties of 2209 duplex stainless steel fabricated by wire arc additive was analyzed. It was found that solution treatment at 1100°C for 2 hours and tempering at 300°C for 2 hours can effectively improve the grain inhomogeneity of 2209 duplex stainless steel, eliminate χ2 and harmful brittle phases, and take into account the mechanical properties and corrosion resistance. Compared with the original deposition state, the hardness and yield strength increased by 10% and 31.8% to 245.6 HV and 499.7 MPa, which meet the requirements of engineering propellers. Electron back-scattered diffraction studies showed that the grains became refined and austenite maintained <101>//Z orientation after solution heat treatment. Many small-angle grain boundaries were present in both the original sample and the solid solution, but further tempering transformed the small-angle grain boundaries into large-angle grain boundaries. [ABSTRACT FROM AUTHOR]

To enhance the applicability of dual-phase high-entropy alloys (HEAs) like Fe32Cr33Ni29Al3Ti3, fabricated via laser beam power bed fusion (LB-PBF), a focus on improving their mechanical properties is essential. As part of this effort, heat treatment was explored. This study compares the microstructure and mechanical properties of the as-printed sample with those cooled in water after undergoing heat treatment at temperatures ranging from 1000 to 1200 °C for 1 h. Both pre- and post-treatment samples reveal a dual-phase microstructure comprising FCC and BCC phases. Although heat treatment led to a reduction in tensile and yield strength, it significantly increased ductility compared to the as-printed sample. This strength-ductility trade-off is related to changes in grain sizes with ultrafine grains enhancing strength and micron grains optimizing ductility, also influencing the content of FCC/BCC phases and dislocation density. In particular, the sample heat-treated at 1000 °C for 1 h and then water-cooled exhibited a better combination of strength and ductility, a yield strength of 790 MPa, and an elongation of 13%. This research offers innovative perspectives on crafting dual-phase HEA of Fe32Cr33Ni29Al3Ti3, allowing for tailorable microstructure and mechanical properties through a synergistic approach involving LB-PBF and heat treatment. [ABSTRACT FROM AUTHOR]

A single body-centered cubic (BCC)-structured AlCoFeNi medium-entropy alloy (MEA) was prepared by the selective laser melting (SLM) technique. The hardness of the as-built sample was around 32.5 HRC. The ultimate tensile strength (UTS) was around 1211 MPa, the yield strength (YS) was around 1023 MPa, and the elongation (El) was around 10.8%. A novel BCC + B2 + face-centered cubic (FCC) structure was formed after aging. With an increase in aging temperature and duration, the number of fine grains increased, and more precipitates were observed. After aging at 450 °C for 4 h, the formed complex polyphase structure significantly improved the mechanical properties. Its hardness, UTS, YS, and El were around 45.7 HRC, 1535 MPa, 1489 MPa, and 8.5%, respectively. The improvement in mechanical properties was mainly due to Hall–Petch strengthening, which was caused by fine grains, and precipitation strengthening, which was caused by an increase in precipitates after aging. Meanwhile, the FCC precipitates made the alloy have good toughness. The complex interaction of multiple strengthening mechanisms leads to a good combination of strength, hardness, and toughness. [ABSTRACT FROM AUTHOR]

This article discusses the use of Additive Manufacturing (AM) in automotive engineering, specifically focusing on the reliability of AM for advanced powertrain components. The study evaluates the mechanical behavior and microstructure features of samples made of AM 17-4PH steel, including engine exhausts, drive shafts, gearbox components, braking systems, and conrods. The researchers analyze the effects of sample geometry, size, and heat treatments on the properties of the samples. The study aims to provide insights for designing efficient prototypes using AM alloys and technology. The article also includes a list of references to other research papers and theses related to the fabrication and properties of stainless steel using AM techniques, providing valuable insights for researchers and engineers in the field. [Extracted from the article]

CoCrFeNiMn high-entropy alloy coatings were deposited on compacted graphite iron (CGI) by plasma transfer arc cladding to strengthen and improve the wear resistance (performance) of the surface. The effects of different heat treatment processes on the microstructure and mechanical properties of the CoCrFeNiMn coatings were investigated. Compared with the deposited coating, the single FCC phase in the heat-treated coatings was retained, the grain size of the columnar dendrites decreased, the spacing between the dendrites increased, and the Cr-rich precipitated phase in the grain boundary increased. The heat treatment process had a positive influence on the microhardness and wear resistance of the coatings. The microhardness of the coatings increased after heat treatment. After heat treatment at 660 °C for 90 min, the coating had the highest microhardness of 563 ± 6.9 HV0.2, and it had the best wear resistance. [ABSTRACT FROM AUTHOR]

This paper adopted the new process of double-sided oscillation laser autogenous backing welding and double-sided oscillation laser–TIG hybrid filling welding to achieve 80 mm thick SA-738Gr.B steel narrow gap welding in the horizontal position. The microstructure, mechanical properties, and residual stress of the welded joints in the as-welded (AW) state and in the post-weld heat treatment (PWHT) state were analyzed comparatively. The results show that because of the high-temperature tempering effect of PWHT, the microstructure of the welded joint is transformed into a high-temperature tempered microstructure with the increase in alloy carbide precipitation. The grains growth of the backing weld and the base material is obvious. The relative frequency of the high-angle grain boundary of the weld increases. Under the PWHT, the tensile strength of the welded joint decreases, and the residual stresses of the welded joint are redistributed and reduced significantly. [ABSTRACT FROM AUTHOR]

Aluminum alloy plates with varying properties were prepared through the superposition friction stir processing of three different aluminum alloys with friction stir joining technology and subjected to solid solution aging. Experimental results showed that friction stir joining yielded a relatively smooth aluminum alloy surface gradient change plate. The plate surface presented a circular superposition trajectory with a clear outline and a rough surface with a flying edge during preparation. The three superimposed aluminum alloy plates achieved good fusion. In particular, fusion was most evident between the uppermost 5052 aluminum alloy and the middle layer of the 6061 aluminum alloy. The fusion of the middle layer of the 6061 aluminum alloy and the lower layer of the 7075 aluminum alloy weakened, and an obvious dividing line was observed. The average Vickers hardness values of the uppermost and undersurfaces of the samples heat-treated at 540°C were the highest, which were 1.34 and 119.06% higher than those of the samples without heat treatment, respectively. The most notable cross-section Vickers hardness gradient was obtained at the solution temperature of 500°C. [ABSTRACT FROM AUTHOR]

Cylinder liners, considered a crucial component of internal combustion (IC) engines, often require excellent mechanical properties to ensure optimal engine performance under elevated temperatures, pressures, and varying loads. In this work, a new low-alloy cylinder liner, incorporating a low content of molybdenum, copper, and chromium into gray cast iron, was fabricated using a centrifugal casting process. Subsequently, the heat treatment processes were designed to achieve bainite microstructures in the cylinder liner through rapid air cooling, isothermal transformation, and tempering. The effects of different air-cooling rates and tempering temperatures on the microstructure evolution and mechanical properties of cylinder liner were investigated. The results revealed that during the supercooled austenite transformation process, rapid air cooling at a rate of 14.5–23.3 °C/s can effectively bypass the formation of pearlitic structures and directly induce the formation of bainite structures. Once the temperature exceeded 480–520 °C, hardness and tensile strength increased with the temperature increase owing to the enhancement of the lower bainite content, the reduction of residual austenite, and the precipitation of the fine hard carbides in the matrix. With temperatures above 520–550 °C, the carbide and lower bainite organization coarsened, thereby reducing the hardness and tensile strength of the material. Therefore, the optimal heat treatment parameters were rapid cooling at 14.5–23.3 °C/s rate to obtain bainite, and tempering of 480–520 °C for finer and more uniform bainite. In addition, the results of the characterization of the mechanical properties of the cylinder liner after heat treatment showed that the hardness, tensile strength, and wear resistance were improved with the refinement of the bainite. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has rapidly evolved and is being embraced by major industrial companies. Various metals, including stainless steel, titanium, aluminum alloys, copper, and precious metals, are available in powdered form for AM technologies. This special issue presents 10 articles covering topics such as improving the sintering process for carbon nanotube-based composites, evaluating the heat treatment condition of a stainless steel, examining crack growth in additively manufactured materials, investigating the microstructure of HSLA steel components, exploring the use of non-destructive testing for AM parts, and discussing the formation of adiabatic shear bands in nickel-based superalloys. These contributions provide valuable insights into optimizing additive manufacturing processes and applications using metal powders. [Extracted from the article]

The effect of heat treatment on microstructure, mechanical properties, and corrosion resistance of 410NiMo super martensitic stainless steel applied by Submerged Arc Welding on 21CrMoV5-11 sublayer has been investigated. The cladded steel was heat treated at different cycles which were; single stage heat treatment (600 °C-6 h), double stage heat treatment (700 °C-2 h & 600 °C-6 h), and austenitizing followed by double stage heat treatment cycles. Results revealed that austenitizing at 1000 °C followed by a double stage treatment improved the impact energy (75j) more than other cycles, due to the formation of austenite and dissolution of carbides and delta ferrite, while the lowest hardness was observed for the welded specimens heat-treated at 600 °C (318HV). It was further shown that the best corrosion resistance (icorr (A/cm2) = 1.02E−9 ± 5E−11 and Ecorr(Vvs Calomel) = − 0.132 ± 0.007) for the cladded steel was obtained by austenitizing the specimen at 1150 °C followed by the double stage treatment, due to the complete dissolution of the delta ferrite phase, chromium carbides, and homogeneous chrome distribution in the clad layer. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of high‐manganese steel (HMnS) fabricated using laser‐directed energy deposition (LDED) with Fe–Mn–4Cr–0.4C alloys with Mn contents of 13, 18.5, and 24 wt% are investigated. Additionally, the effect of annealing heat treatment on the microstructure and mechanical properties of the deposited HMnS is examined. Regardless of the manganese content, the deposited HMnS exhibits a fine microstructure without any defects (cracks or voids) and a strong fibrous texture along the <001>//building direction of the primary austenite phase. In addition, regardless of the manganese content, the grain size increases during annealing heat treatment, and the hardness decreases as the annealing temperature increases. The strength tends to decrease as the Mn content increases in the as‐built state. In addition, regardless of the Mn content, the yield strength and ultimate tensile strength tend to decrease owing to the effect of annealing heat treatment. Although the maximum elongation of 18.5Mn and 24Mn does not change significantly upon heat treatment, the maximum elongation of 13Mn is greatly reduced by annealing. The deformation behavior of HMnS is characterized by transformation‐induced plasticity (TRIP) for 13Mn and both TRIP and twinning‐induced plasticity for 18.5Mn and 24Mn. [ABSTRACT FROM AUTHOR]

The effects of heat treatment on the microstructure of Al0.78CoCrFeNi alloy fabricated by laser additive manufacturing was studied by OM, SEM, TEM and XRD. The results show that the grain structure of Al0.78CoCrFeNi alloy changes obviously with different solution treatments and times. The grain size of the alloy is uniform, and B2 phase is uniformly distributed in the grain after 1050°C × 45 min and 720°C × 9 h heat treatment. B2 phase nucleates preferentially at the dislocation entanglement in the grain, and the newly precipitated B2 phase particles are small and large, mainly distributed in the grain. With the increase of aging temperature and time, the B2 phase of small particles grows up gradually and distributes uniformly in the grain. The microstructure observed by TEM shows that in addition to the B2 phase in the grain, an ordered phase γ′-Ni3Al completely coherent with the matrix appears near the grain boundary. [ABSTRACT FROM AUTHOR]

Selective laser melting(SLM) can achieve nearly net-shape complex parts of GH3536 alloy, and its high temperature mechanical properties are important indicators for safe service. The effect of heat treatment on microstructure and high temperature tensile properties of SLM GH3536 alloy were studied. The heat treatment at 1225 t for 1 h was carried out to explore the regulation mechanism of microstructure and properties. The results show that heat treatment can effectively eliminate the cellular subgrain structure inside the grains, which significantly enhances the dislocation slip ability. The tensile elongations at room temperature, 650 t and 815 t are increased by 75%, 92% and 683%, respectively. In addition, the decrease of the aspect ratio of the columnar grains significantly reduces the anisotropy in the heat-treated sample. The fracture analysis shows that the fracture mode of the heat-treated sample changes from intergranular fracture to mixed fracture with the increase of tensile environment temperature. Key words: selective laser melting; GH3536 alloy; microstructure; high temperature tensile; fracture mode [ABSTRACT FROM AUTHOR]

The effect of heat treatment on the microstructure and high temperature mechanical properties of SLM GH4169 alloy was studied by using a self-developed in-situ high temperature tensile device. The results show that the grain morphology of as-built alloy changes from columnar crystal to equiaxed crystal after homogenization+solid solution+aging treatment (HSA), coupling with Laves phase dissolution, and a large amount of y' and y" strengthening phase precipitates. At 650 t, the yield strength and tensile strength of the as-built sample are 574 MPa and 740 MPa, while the yield strength and tensile strength of HSA sample are 818 MPa and 892 MPa respectively, which are 42.5% and 20.1% higher than that of the deposited alloy. The deformation process can be further characterized by in-situ tensile testing. The surface grain undulation of the as-built sample gets larger, the coordinated deformation ability becomes stronger, and the plastic flow ability gets better.The cracks in the as-built sample are originated around the Laves phase, spreading along the dendrite towards the maximum shear stress, and shear fracture occurs after necking of the sample. In HSA samples, the cracks are initiated around carbides and propagating along the grain boundaries. The fracture mode is a mixed type, involving both intergranular and transgranular fractures. [ABSTRACT FROM AUTHOR]

Herein, 347 austenitic stainless steel parts are made by the wire arc additive manufacturing process. Then, the effects of solution heat treatment at 1150 °C for 3 h followed by NbC stabilizing heat treatment at 950 °C for 1 h on the properties of the alloy are investigated. Results show that after solidification, δ‐ferrite and NbC carbide particles are formed in the γ matrix while heat treatment eliminates the δ phase. Tensile test results show that for the as‐prepared alloy, yield strength varies between 336 and 352 MPa, tensile strength between 559 and 589 MPa, and elongation between 50% and 58%. However, heat treatment results in a 20–22% decrease in yield strength, a 5–10% decrease in tensile strength, and a 5% decline in elongation. The potentiodynamic (PD) polarization test results show that the ICORR and the corrosion rate of the WAAM 347 stainless steel in the as‐prepared condition are separately 4.9 and 5.6 times higher than the wrought alloy. After heat treatment, the ICORR increases from 5.84 × 10−6 A cm−2 in the as‐prepared alloy to 6.68 × 10−6 A cm−2 and the corrosion rate from 0.0678 to 0.0776 mm y−1. This means that the heat treatment deteriorates the corrosion resistance of the WAAM 347 stainless steel alloy by about 14%. [ABSTRACT FROM AUTHOR]

The article aims to characterize Hadfield steel by analyzing its chemical composition, mechanical properties, and microstructure. The study focused on the twinning-induced work hardening of the alloy, which led to an increase in its hardness. The experimental data show that the material hardness at the surface improved considerably after solution heat treatment and work hardening, reaching more than 750 HV. By contrast, the hardness of the material core in the supersaturated condition was about 225 HV. The chemical and phase compositions of the material at the surface were compared with those of the core. The microstructural analysis of the steel revealed characteristic decarburization of the surface layer after solution heat treatment. The article also describes the effects of heat treatment on the properties and microstructure of Hadfield steel. The volumetric (qualitative) analysis of the computed tomography (CT) data of Hadfield steel subjected to heavy dynamic loading helped detect internal flaws, assess the material quality, and potentially prevent the structural failure or damage of the element tested. [ABSTRACT FROM AUTHOR]

We produced silicon-containing CrFeCoNi high-entropy alloy (HEA) deposits using the low-pressure plasma spraying method and assessed their structural and characteristic properties. The alloy deposits, once manufactured, underwent a heat treatment process, during which we closely examined the formation of precipitates. These HEAs were fabricated on substrates, regardless of whether they were subjected to water-cooling or not. In the case of both deposits acquired with and without water-cooling of the substrates, diffraction peaks corresponding to the face-centered cubic (FCC) phase were clearly observed when subjected to high temperature heat treatment at 1273 K. Additionally, we identified the presence of silicon-containing compounds on the deposits. As the heattreatment temperatures increased, we observed the coarsening of the precipitates. Notably, within the crystal granules of the water-cooled as-sprayed deposits, nanoscale precipitates were generated. Among all the samples, deposits heat-treated at 973 K exhibited the highest precipitate area fraction and hardness. This suggests a correlation between the heat treatment temperature and the resulting properties of the HEA deposits, with 973 K being the point at which the highest precipitate area fraction and hardness were achieved. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present work investigates the influence of post-weld heat treatments (PWHT) on friction stir welded joints of AA2014 and AA7075 dissimilar alloys. Four different PWHT conditions, namely artificial aging (AA), solution treatment and artificial aging, solution treatment (ST), and natural aging (NA), were applied to study their influence on weld strength and microstructural properties. Natural aging showed the best strength of 347.5 ± 7.78 MPa among all the PWHT conditions. In contrast, other PWHT conditions deteriorated the tensile strength compared to as-welded joints. The highest elongation of 10.76 ± 1.27% was observed in NA, while the lowest was in AA among all the welded joints. The fracture location shifted to the stir zone (WNZ) in AA and ST. In contrast, in other PWHT welds, fractures occurred outside the weld region. Abnormal grain growth was observed in the WNZ of the ST joint. Microhardness improvement was observed in WNZ of ST and NA weld, while a lower value was found in the remaining ones. Fracture study revealed that fracture mode was brittle in AA whereas ductile in other joints. [ABSTRACT FROM AUTHOR]

The attractive mechanical properties of 7075 alloy, such as its high strength-to-weight ratio and fracture toughness, have received special attention in the automotive and aerospace industries. However, welding as a fabrication process has a detrimental effect on this alloy's properties which affects its mechanical performance. In this work, to compensate for the loss in mechanical properties caused by welding, proper heat treatment operations are adopted. To this end, 1.5 mm AA7075 sheets were first preheated and butt welded using the gas tungsten arc welding process. The welded sample was solution heat treated, quenched, and then artificially aged. Microhardness tests showed an increase of hardness in all zones of the aged specimen compared to those of the original welded blank before heat treatment. A maximum microhardness value of 180 HV was recorded in the heat-affected zone of the aged specimen. In addition, elongation at break, and strength (yield, tensile, and fracture) of the original welded blank increased by about 50% after the artificial aging operation. [ABSTRACT FROM AUTHOR]

The impact of high-speed micron-sized metallic particles during cold spray additive manufacturing (CSAM) often leads to non-uniform plastic deformation, resulting in work hardening effects that can cause brittleness, poor mechanical properties, and anisotropy in the deposits. This study aimed to characterize the wear, mechanical properties, and mechanical anisotropy of 2024 aluminum alloy deposits and investigate the effects of heat treatments (annealing, solution, aging treatment) on improving these properties. The results revealed that the mechanical property anisotropy of the As-sprayed deposits was not significant. Specifically, the tensile strength of the As-sprayed deposits measured at angles of 0º, 45º, and 90º from the spraying direction are 58 MPa, 52 MPa, and 41 MPa, respectively. Annealing was found to decrease wear resistance and hardness but had a positive impact on mechanical properties. Solution and aging treatment proved to be effective in improving wear resistance. For the solution-treated deposits, the measured tensile strength and elongation at angles of 0º, 45º, and 90º from the spraying direction are 108 MPa, 114 MPa, and 101 MPa, and 6.5%, 5.8%, and 4.8%, respectively. It is worth noting that heat treatment improves the bonding quality, however, the presence of pores generates during the heat treatment limits further improvements in mechanical properties. Overall, this study highlights the importance of heat treatments in enhancing the mechanical properties, wear resistance, and mechanical anisotropy of 2024 aluminum alloy deposits produces through CSAM. [ABSTRACT FROM AUTHOR]

The effect of heat treatment on the microstructure and tensile properties of an as-cast Al0.6CoCrFeNi high-entropy alloy (HEA) was investigated in this paper. The results show that the as-cast Al0.6CoCrFeNi HEA presents a typical FCC dendrite morphology with the interdendritic region consisting of BCC/B2 structure and heat treatment can strongly affect the microstructure and mechanical properties of HEA. Microstructure analysis revealed the precipitation of a nano-sized L12 phase in the FCC dendrite and the formation of the FCC and σ phases in the interdendritic region after annealing at 700 °C. The coarse B2 phase was directly precipitated from the FCC dendrite in the 900 °C-annealed sample, with the coexistence of the B2, FCC, and σ phases in the interdendritic region. Then, the interdendritic region converted to a B2 and FCC dual-phase structure caused by the re-decomposition of the σ phase after annealing at 1100 °C. The tensile test results show that the 700 °C-annealed HEA presents the most significant strengthening effect, with increments of corresponding yield strength being about 107%, which can be attributed to the numerous nano-sized L12 precipitates in the FCC dendrite. The mechanical properties of 1100 °C-annealed alloy revert to a level close to that of the as-cast alloy, which can be attributed to the coarsening mechanism of B2 precipitates and the formation of a soft FCC phase in the interdendritic region. The observed variation in mechanical properties during heat treatment follows the traditional trade-off relationship between strength and plasticity. [ABSTRACT FROM AUTHOR]

Today, 7xxx aluminum alloys are widely used in aerospace and other fields due to their excellent properties such as low density, high specific strength, and good processing performance. The heat treatment process of 7xxx aluminum alloy is crucial in controlling the strengthening phases and grain size, which is a significant way to enhance the alloy's performance. In this study, solution heat treatment tests of 7050 aluminum alloys were carried out at different temperatures, ranging from 440 °C to 470 °C, with a holding time ranging from 0.5 h to 8 h, using a DIL 805A thermomechanical test machine. The microstructural evolution during the solution heat treatment was characterized using an optical microscope (OM), a scanning electron microscope (SEM), and a transmission electron microscope (TEM). The effects of the solution parameters on the alloy's microhardness were analyzed using a digital Vickers microhardness tester. According to the ASTM E112-13 standard, The Anelli grain growth models were established to illustrate the grain size evolution during solution heat treatment, and a modified Anelli grain growth model was established. The results indicated that the grain size significantly increases with the increase in the solution heat treatment time and temperature. The Anelli grain growth model can illustrate the phenomenon of grain growth more accurately in the solution heat treatment process of 7050 aluminum alloy. It was found that prolonging the time and elevating the temperature of the solution heat treatment reduced the microhardness of the aluminum alloy because of the dissolution of the precipitates. [ABSTRACT FROM AUTHOR]

AlFeCoCrNiTi0.2 Ugh entropy alloy was prepared by vacuum casting and annealed at 600,800 and 1 100 C respectively. The microstructure and mechanical properties of the alloy with different heat treatment temperatures were studied by means of Scanning Electron Microscopy (SEM), energy dispersive analysis(EDS), X- ray diffractometer(XRD), Nano indentation instrument and universal mechanical testing machine. The results show that the as-cast and heat-treated AlFeCoCrNiTi0.2 High-entropy alloys are body-centered cubic structure. After heat treatment,BCC1 predicates BCC2 phase to form a biphasic structure (primary phase BCC1 + precipitated phase BCC2). At 600 C,the hardness of the alloy is 672 HV,the plastic modulus is 655. 7 Gatha pressing depth is 283. 4 nm, the compression plasticity is 28%,and the breaking strength is 1. 75 GA. The hardness of 800 C and 1 100 C alloy decreases, manly due to the decomposition of BCC phase to form a biphasic BCC (BCC1 +BCC2) sold solution structure, which reduces the strength of the alloy. [ABSTRACT FROM AUTHOR]

This paper investigated the mechanical properties and microstructures of different samples of H13 steel after they underwent various heat treatment processes. It provided a detailed analysis of the microstructure and mechanical properties under different processes and approached the topic from a theoretical perspective. The phase composition of each sample remained unchanged after undergoing different heat treatment processes. Despite the vacuum gas quenching (H1) sample being guaranteed a hardness of 58.47 HRC, its toughness fell below expectations at a mere 46.75 J. Notably, the microstructure of the sample which underwent the H1 process and the cryogenic (H2) treatment exhibited a finer grain size and higher toughness compared to the sample which only underwent the H1 process without the cryogenic treatment. Its toughness was 70.19 J, but its hardness slightly decreased to 57.47 HRC. Following the application of oil quenching and cryogenic treatment (H3), the hardness of the sample significantly increased, reaching a remarkable 58.38 HRC. Additionally, the sample exhibited good impact resistance, with a measurement of 74.25 J. Before the H2 process, the sample which underwent the spheroidizing annealing process (H4) had a higher hardness compared to the sample without spheroidizing annealing. At the same time, when comparing the above four samples, the sample that underwent the H4 process exhibited the best toughness, with a value of 86.94 J, while still maintaining a hardness of 57.85 HRC; thus, it achieved an ideal balance between strength and toughness. Therefore, the optimal heat treatment process for high-carbon H13 steel was spheroidizing annealing followed by vacuum gas quenching and then cryogenic treatment. [ABSTRACT FROM AUTHOR]

The effect of tempering and of quenching + tempering including step tempering on the microstructure and properties of centrifugally cast rolls made of high-chromium cast iron HCCI is studied. It is shown that the cast iron microstructure is a matrix consisting of retained austenite and martensite and surrounded by a eutectic. Tempering of cast iron without quenching reduces the amount of retained austenite in the structure but has a little effect on the hardness. Quenching improves significantly the uniformity of the microstructure and increases the hardness, which grows still more after tempering. The quenching temperature affects significantly the martensitic transformation temperature Ms , which decreases with increase of quenching temperature; the step quenching has a stronger effect. The hardness of the roll after quenching from 1100°C with a step at 560°C and tempering at 500°C is 64.4 HRC, which is much higher than the hardness of 58.3 HRC after tempering at 500°C without quenching. [ABSTRACT FROM AUTHOR]

The effect of heat treatment modes on the microstructure, microhardness and electrical conductivity of an aluminum metal matrix composite (MMC) reinforced with Al2O3 nanoparticles in an amount of 2.5 wt.% is studied. The MMC is treated by quenching from 510, 530 or 550°C and subsequent artificial aging at 140, 160, 180, 200 or 220°C. The cast composite has a Vickers microhardness of 36 HV and an electrical conductivity of 45% IACS. The heat treatment raises the hardness and the conductivity of the composite. Quenching from 530°C and aging at 200°C produce the highest microhardness (46 HV); quenching from 530°C and aging at 180°C produce the highest conductivity (50% IACS). [ABSTRACT FROM AUTHOR]

In this study, 7075 aluminum alloy welding wire with TiB2 nanoparticle reinforcement as an additive together with the variable polarity TIG welding arc as a heat source were applied to produce thin-walled deposited layer samples. Results indicated that the performance of the deposited structure of 7075 aluminum alloy with a TiB2 reinforcement phase was significantly improved compared to the deposited structure of ordinary 7075 aluminum alloy welding wire. Meanwhile, the precipitation of the TiB2 reinforcement phase was insufficient within the structure, and the enhancing effect could not be fully exerted. Moreover, the 7-series aluminum alloy contained a large amount of Zn and Mg elements inside. If the soluble crystalline phase was not fully dissolved, severe stress corrosion could be caused, which inevitably led to a decrease in the mechanical properties. To further improve the performance of the deposited layer, a T6 heat treatment process was performed at 470 °C for 2 h, followed by rapid cooling with distilled water and artificial aging at 120 °C for 24 h. After heat treatment, many second phases appeared in the microstructure of the deposited layer, and the tensile strength increased from (361.8 ± 4.8) MPa to (510.2 ± 5.4) MPa together with the elongation which increased from (9.5 ± 0.5) % to (10.2 ± 0.4) %. The fracture mode of the fracture was a ductile fracture along grain boundaries. The microhardness increased from (145 ± 5) HV to (190 ± 4) HV and exhibited good corrosion resistance in a 3.5% NaCl solution corrosion test. [ABSTRACT FROM AUTHOR]

The new cast steel with a chemical composition of Fe-(0.85-0.95)C-(1.50-1.60)Si-(2.40-2.60)Mn-(1.0-1.2)Al-(0.30-0.40)- Mo-(0.10-0.15)V-(1.0-1.1)Ni (all in wt.%) was investigated in aspect of formation of the multiphase microstructure leading to high strength and ductility. Two types of heat treatment technologies were developed. The first one involves softening annealing at a temperature of 650°C for 4 hours, heating up to 950°C and holding for 2 hours, and then fast cooling down to 200°C and isothermally treated for 2 hours. The second one involves homogenizing annealing at 1100°C for 6 hours, then cooling with furnace down to 950°C and holding for 2 hours, then fast cooling down to 200°C and isothermally treated for 2 hours. A unique microstructure of cast steel consisting of martensite and retained austenite plates of various thicknesses and volume fractions was obtained. Additionally, nanometric transition carbides were noticed after the above-mentioned heat treatments. This microstructure ensures high hardness, strength and plasticity (Rm = 1426 MPa and A = 9.5%), respectively, due to the fact that TWIP/TRIP processes occur during deformation related to the high volume fraction of retained austenite, which the stacking fault energy is above 15 mJ/m–2 resulting from the chemical composition of the investigated cast steel. [ABSTRACT FROM AUTHOR]

In this study, the effects of heat treatment on the microstructure and strength (micro-hardness) of an aluminum–lithium (Al-Li) base alloy containing copper (Cu) and scandium (Sc) were investigated, with a view to enhancing the alloy performance for aerospace applications. The heat treatment conditions were investigated to understand the precipitation behavior and the mechanisms involved in strengthening. Aging was carried out at temperatures of 130 °C and 150 °C for aging times of 1 h, 2.5 h, 5 h, 10 h, 15 h, 25 h, 35 h, and 45 h at each temperature for Al-Li alloy and at 160 °C, 180 °C, and 200 °C for aging times of 5 h, 10 h, 15 h, 20 h, 25 h, and 30 h at each temperature for Al-Li-Cu and Al-Li-Cu-Sc alloys. The investigation revealed that both solution heat treatment and artificial aging had a notable impact on strengthening the hardness of the alloy. This effect was attributed to the characteristics of the precipitates, including their type, size, number density, and distribution. The addition of copper (Cu) and scandium (Sc) was observed to have an impact on grain size refinement, while Cu addition specifically affected the precipitation behavior of the alloy. It led to remarkable changes in the number density, size, and distribution of T1 (Al2CuLi) and θ' (Al2Cu) phases. As a result, the hardness of the alloy was significantly improved after the addition of Cu and Sc, in comparison with the base Al-Li alloy. The best heat treatment process was determined as: 580 °C/1 h solution treatment +150 °C/45 h artificial aging for Al-Li alloy and 505 °C/5 h solution treatment +180 °C/20 h artificial aging for Al-Li-Cu and Al-Li-Cu-Sc alloys. [ABSTRACT FROM AUTHOR]

Herein, amorphous manganese dioxide (AMO) is prepared by the liquid‐phase coprecipitation method, the effect of heat treatment temperature on the microstructure, and phase composition of AMO and the electrochemical properties as cathode materials for aqueous Zn–MnO2 batteries are investigated. The results show that the AMO didn't crystallize at 250 °C, but its structure stability increases. When the temperature is 350 and 400 °C, part of the AMO crystallizes into rod‐shaped nano‐α‐MnO2 crystals. At 540 °C, the products crystallize into nano‐α‐MnO2 crystals. Continuing to increase the temperature to 650 °C, the structural stability of the products is further improved. Heat treatment leads to reduced specific surface area and porosity of the material, which in turn leads to reduced specific capacity and cycling stability. In addition, the heat‐treated products show a sharp drop in capacity during the discharge process; this was because the volume change caused by the irreversible phase change of the electrode material is difficult to release in the anisotropic crystal, resulting in the collapse of the structure. This study shows that unheated AMO is better than heat‐treated AMO as a cathode material for aqueous Zn–MnO2 battery cathode material in terms of overall performance and cost. [ABSTRACT FROM AUTHOR]

The pseudoelasticity behavior of memory‐steels has recently gained attention for applications in seismic‐resistant structures. The pseudoelasticity can be used to reduce residual deformations in building structures subjected to seismic loading. Fe‐based shape memory alloys (Fe‐SMA), which is also called as memory‐steel, have gained much attention because of their strong shape memory behavior and low material manufacturing cost, which justify their large‐scale application in construction. This research investigated the effects of heat treatment on microstructure and pseudoelasticity of a memory‐steel (Fe‐17Mn‐5Si‐10Cr‐4Ni‐1(V,C) %wt.). Various solution‐annealing treatments from 1000 to 1200 °C for 2 h and aging from 650, 750 and 850 °C were applied to investigate the microstructural evolution and pseudoelasticity behavior of the alloy. The results showed that increasing the solution annealing temperature caused grain growth and pseudoelasticity loss. On the other hand, the precipitation of (Cr,V)Cs after aging resulted in an improved pseudo‐elasticity. The large elastic strain field, which forms near the carbide precipitates, improves the pseudoelasticity. Furthermore, precipitates can provide preferential nucleation sites for the martensite phase and a high density of stacking faults in the austenite matrix. The study concludes that the best pseudoelasticity behavior was achieved after an aging at 750°C for 6 h. [ABSTRACT FROM AUTHOR]

The combination of precipitation-hardening stainless steels (PH-SS) and laser powder bed fusion (LPBF) enables the manufacturing of tools for plastic injection moulding with optimised geometry and conformal cooling channels, with potential benefits in terms of productivity, part quality, and tool duration. Moreover, the suitability of LPBF-manufactured PH-SS in the as-built (AB) condition to be age-hardened through a direct aging (DA) treatment enables a great heat treatment simplification with respect to the traditional solution annealing and aging treatment (SA). However, plastic injection moulding tools experience severe thermal cycles during their service, which can lead to over-aging of PH-SS and thus shorten tool life. Therefore, proper thermal stability is required to ensure adequate tool life and reliability. The aim of the present work is to investigate the aging and over-aging behaviour of a commercially available PH-SS (AMPO M789) manufactured by LPBF in the AB condition and after a solution-annealing treatment in order to evaluate the effect of the heat treatment condition on the microstructure and the aging and over-aging response, aiming at assessing its feasibility for plastic injection moulding applications. The AB microstructure features melt pool borders, oriented martensite grains, and a cellular solidification sub-structure, and was retained during aging and over-aging. On the other hand, a homogeneous and isotropic martensite structure was present after solution annealing and quenching, with no melt pool borders, cellular structure, or oriented grains. The results indicate no significant difference between AB and solution-annealed and quenched specimens in terms of aging and over-aging behaviour and peak hardness (in the range 580–600 HV), despite the considerably different microstructures. Over-aging was attributed to both the coarsening of strengthening precipitates and martensite-to-austenite reversion (up to ~11 vol.%) upon prolonged exposure to high temperature. Based on the results, guidelines to aid the selection of the most suitable heat treatment procedure are proposed. [ABSTRACT FROM AUTHOR]

The effect of heat treatment on the microstructure, microhardness, and structural-phase state of the samples of the ChKh3 low-alloy wear-resistant chromium cast iron is studied. The metallographic analysis is performed using a Carl Zeiss Axio Observer Z1m metallographic microscope and ThixoMet PRO software. The heat treatment of the samples is carried out in a SNOL furnace equipped with a Termodat 16-E3 PID controller. After 2-h-long quenching at a temperature of 890°C, the samples are removed from the furnace and cooled in still air. After cooling to a temperature of 40–50°C, the samples are tempered at a temperature of 180–200°C for 2 h. The samples cooled after tempering have a hardness of 54–56 HRC compared to a hardness of 320–340 HB in the cast state. The results for heat treatment show that the main contribution to an increase in the hardness of the ChKh3 wear-resistant chromium cast iron is provided by a significant increase (by a factor of 2–2.5) in the hardness of the metal matrix due to solid-solution hardening and partial precipitation of fine inclusions (carbide particles). Tests of heat-treated shot blast blades made of the ChKh3 cast iron show an increase in service life by a factor of 8–11 compared to cast blades not subjected to heat treatment, and a factor of 1.5–2 compared to serial shot blast blades, made of the 510Cr2 cast iron in China. [ABSTRACT FROM AUTHOR]

Cu–15Ni–8Sn alloy is the best choice to replace beryllium bronze alloy. This alloy has unparalleled application value in aerospace, ocean engineering, electronic information, equipment manufacturing, and other fields. However, the application of Cu–15Ni–8Sn alloy is challenged and limited because of a series of problems in its preparation and processing, such as easy segregation, difficult deformation, and discontinuous precipitation. It is an effective way to improve the comprehensive properties of Cu–15Ni–8Sn alloy using alloying design and process optimization to control the as-cast, deformed, and heat-treated microstructures. At present, it is a hot spot for scholars to study. In this paper, the grade generation, system evolution, and preparation technology development of Cu–15Ni–8Sn alloy are comprehensively reviewed. The phase transformation sequence of the Cu–15Ni–8Sn alloy is discussed. The influence of the type, amount, and existing form of alloying elements on the strength of Cu–15Ni–8Sn alloy and its mechanism are systematically summarized. Furthermore, the latest research progress on the effects of solid solution, cold deformation, and aging on the phase structure transformation and mechanical properties of Cu–15Ni–8Sn alloy is summarized. Finally, the future development trend of the Cu–15Ni–8Sn alloy is projected. The research results of this paper can provide a reference for the control of the microstructure and properties of high-performance Cu–15Ni–8Sn alloys used in key fields, as well as the optimization of the preparation process and alloy composition. [ABSTRACT FROM AUTHOR]

Microstructure and composition significantly influence the physical properties of thin films. Therefore, these can be adapted to enhance the functionality of thin films for practical applications. Herein, the anomalous microstructural evolution of sputtered GeO2 thin films based on postdepositional heat treatments is reported. Temperature‐dependent microstructural variations are investigated systematically via a combinatorial postdepositional heat treatment employing a natural thermal gradient in a tube furnace. Heat treatment under an oxidizing atmosphere results in a transition from the amorphous phase to the quartz phase, and subsequent heat treatments under a reducing atmosphere cause H2O‐incorporated chemical reactions. Hence, these conditions create unique microstructural features and yield optical transmittance variations in the GeO2 thin films. The phase transition induces the formation of spherulitic hexagonal GeO2 crystallites, and further increase in the temperature promotes the agglomeration of crystallites in the amorphous matrix. The incorporation of H2O results in the growth of the microstructure, and the chemical reduction to Ge metal begins to generate small granules from the boundary of the microstructures. The experimental results and proposed mechanisms presented herein for the microstructural and compositional changes serve as references for designing the physical properties of thin films. [ABSTRACT FROM AUTHOR]

Fasteners are widely used in automobile, electronic and other fields, and the demand for high performance fastener materials is increasingly urgent. 10B21 mild steel has the advantages of good plasticity, obvious heat treatment effect and so on. It is used to produce fasteners below grade 9.8. In this paper, the domestic 10B21 boron steel as the research object, through quenching, tempering and other heat treatment, change its structure from ferrite to tempered martensite, in order to improve the strength and hardness. [ABSTRACT FROM AUTHOR]

The effect of vacuum heat treatment on the interface microstructure and tribological property of Cu-coated Ti--6Al--4V alloy is investigated herein. After the vacuum heat treatment process, a diffusion layer is formed at the interface between the Cu coating and the Ti--6Al--4V substrate. The formed intermetallic compounds at the interface between the Ti--6Al--4V substrate and Cu coating are CuTi2, CuTi, Cu4Ti3, and β-Cu4Ti. The activation energy of intermetallic compound growth in the diffusion zone of Cu-coated Ti--6Al--4V is 126.0 kJmol-1, and the pre-exponential factor is 0.1m2 s-1. The tribological properties of the Cucoated Ti--6Al--4V alloy are best when subjected to diffusion treatment at 700 °C for 300 min, with weight loss reduced by 58.2% compared to the Ti--6Al--4V alloy. The wear resistance of the Ti--6Al--4V alloy can be enhanced by Cu coating and vacuum diffusion heat treatment, and the formation of the Cu--Ti intermetallic compound contributes to this improvement. These findings offer new insights for further advancements in the tribological properties of titanium alloys. [ABSTRACT FROM AUTHOR]

This study investigated the microstructures and tensile properties of as-build and heat-treated (including T6, T2, and T6-T2 treatments) AlSi10Mg samples fabricated by laser powder bed fusion (LPBF). The microstructure analysis revealed that the trend of eutectic Al-Si phase distribution along grain boundaries for heat-treated samples was significantly weakened, and the eutectic Al-Si phase was transformed into Si particles which were uniformly distributed in α-Al matrix. For the T6-T2-treated specimens, the Si content in particles was the highest. Meanwhile, the T6 treatment increased the proportion of equiaxed grains on vertical section most significantly. However, in the wake of heat treatments, the average grain size on horizontal section had little change while the average grain size on vertical section was increased. The properties analysis demonstrated that the T6-T2-treated specimens obtained the best elongation and worst strength. Besides, the T6 treatment eliminated the anisotropy of the LPBFed specimens basically and synergistically obtained the best combination of strength and plasticity. The T6 treatment weakened the direction difference to the greatest extent, whereas the T2 treatment minimized the stress concentration. According to the comparative finding, the Si content in particles played an important part in properties. Besides, the relationship among inverse pole figure (IPF) maps, pole figure (PF) maps, the mass fraction and distribution of Si in Al matrix and Si particle, the grain size, kernel average misorientation (KAM), and mechanical properties under different heat treatments was established, which provided a new idea for the selection of heat treatments on LPBFed parts. [ABSTRACT FROM AUTHOR]