Search

Hydroxyapatite-carbon nanotubes (HA-CNTs) nanocomposite coating was applied by electrophoretic method on anodized Ti alloy to investigate its stability in simulated body fluid (SBF). The biocoating was characterized by using scanning electron microscope (SEM) for microstructure, X-ray diffraction (XRD) for crystallography. The effect of CNTs concentration on the coating properties was also investigated and found out that CNTs up to 5% has various improving effect on the system. It increased corrosion resistance and adhesion of the coating to the substrate and decreased the number of cracks on the coating. The results of the in vitro test showed that the cell viability increased with increasing the concentration of CNTs to 3 wt.% CNTs. [ABSTRACT FROM AUTHOR]

The effect of scandium content on the structure and properties of alloy Al – 4.5% Zn – 4.5% Mg – 1% Cu – 0.12% Zr is determined. The microstructure of the alloy is studied with identification of the phases using an optical microscope and scanning and transmission electron microscopes. The Vickers hardness and the yield strength under heating are determined. The phase diagram is plotted and the nonequilibrium crystallization is described using the Thermo-Calc software and the TTAL5 database. It is shown that addition of 0.1% scandium contributes substantially enough into the growth of the hardness after 3-h annealing at 450°C and into the yield strength after 20-h aging at 175°C. The compositions studied are recommended as a base for designing new refractory alloys based on the Al – Zn – Mg – Cu system. [ABSTRACT FROM AUTHOR]

In this paper, based on the as-cast CuSn10P1 alloy. Semi-solid CuSn10P1 alloy billet was prepared by cold-rolled isothermal treatment strain-induced melting activation (CRITSIMA). The effects of cold-rolling reduction, isothermal temperature, and isothermal time on the microstructure of semi-solid copper alloy billet were studied by metallographic microscope and Image-Pro Plus software. The changes of primary elements in as-cast and semi-solid microstructure were analyzed briefly by a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). The results show that with the increase of cold rolling reduction, the average grain diameter of semi-solid microstructure decreases gradually, the average grain roundness increases first and then decreases, and the liquid fraction of the microstructure remains unchanged. During semi-solid isothermal treatment, with the increase of isothermal temperature and the extension of isothermal time, the average grain diameter increases gradually, the average grain roundness increases first and then decreases, and the liquid fraction increases gradually. When cold rolling reduction is 30%, isothermal temperature is 900 ℃, and isothermal time is 20 min, a better microstructure can be obtained. The average grain diameter, average grain roundness, and liquid fraction of semi-solid alloy billet are 66.45 μm, 0.71, and 12.78%, respectively. Sn and P diffuse from the intergranular liquid to the grain inside during the isothermal treatment from as-cast to semi-solid. [ABSTRACT FROM AUTHOR]

The effects of different Ce content on the microstructure and corrosion resistance of Al-5Mg-3Zn-1Cu alloy in metal mold gravity casting were studied in this paper. The microstructure of the alloy was characterized by scanning electron microscope (SEM) and X-Ray diffractometer (XRD). The corrosivity of all alloys in 3.5 wt.%NaCl solution was studied by electrochemical and immersion corrosion techniques. The results show that the microstructure of the alloy is mainly composed of α-Al, T phase, and Al2Cu phase. Ce can refine the organization of the alloy, but when the addition of Ce is higher than 0.25 wt.%, a massive Ce-rich phase appears in the alloy. The results of a potential polarization test show that the corrosion potential of the alloy increases obviously from −1.253 V to −1.193 V with the increase in Ce content in the alloy. [ABSTRACT FROM AUTHOR]

In this work, static mass analysis method and electrochemical test experiment were used to study the corrosion resistance of Mg-12Gd-3Y-1Sm-0.8Al alloy in different heat treatment states. Optical microscope, scanning electron microscope and x-ray diffractometer were used to analyze microstructure. The result shows: The microstructure of different samples are composed of α-Mg, Mg5Gd, Mg24Y5, Mg41Sm5 and Al2RE phases. Heat treatment can change the morphology and distribution of the precipitates, and the precipitates can affect the corrosion behavior as a cathode, thereby improving the corrosion resistance of the alloy in 3.5% NaCl solution. The relative corrosion rates of the different samples can be ranked as T6>T6-18h>T4>As-cast. After aging treatment, the fine and continuous precipitates act as a barrier to prevent the propagation of corrosion. At this time, the alloy has the strongest corrosion resistance. [ABSTRACT FROM AUTHOR]

In this study, a new alloy material Mg-Zn-Zr (ZK60) was designed for the connecting rod. It was found that the blanks sampled along the vertical direction of an extruded bar crack during the roll forging process. The microstructure and precipitates of the extruded bar were observed and analyzed using optical microscope (OM), scanning electron microscope (SEM) and x-ray diffraction (XRD). The result showed that the Zn, Zr, and MnZn2 precipitates were elongated along the extrusion direction. The mechanical anisotropy was investigated by testing the mechanical properties of the specimens sampling from different angles. Hot deformation behavior was further studied using the Gleeble 3500 thermal-mechanical simulator. The tensile and yield strengths were the highest along the extrusion direction, reaching 347 MPa and 301 MPa, respectively. The deformation resistance was also higher in the extrusion direction than that in the vertical direction. Fracture mechanisms of the sample from different directions were discussed. The ZK60 alloy was more susceptible to failure if the deformation direction was parallel to the bands of segregation area and precipitates. [ABSTRACT FROM AUTHOR]

By means of an electrochemical workstation, hydrogen evolution device, optical microscope (OM) and scanning electron microscope (SEM), the corrosion behaviors of an as-rolled Mg-8%Li alloy with a dual phase structure in 0.9 wt.% NaCl and 3.5 wt.% NaCl solutions have been investigated and compared. The results show that when the immersion time exceeds 8 h, the hydrogen evolution rate of the alloy in the 0.9 wt.% NaCl is 3 times higher than that in the 3.5 wt.% NaCl solution. Moreover, the corrosion behaviors of the alloy are obviously different in the two differently concentrated NaCl solutions. In the 3.5 wt.% NaCl solution, the localized corrosion is much more severe and can occur simultaneously in the interior of both the α-Mg and β-Li matrix phases. However, the localized corrosion in the 0.9 wt.% NaCl solution is obviously weak and mainly occurs at the α-Mg phase. [ABSTRACT FROM AUTHOR]

Solidification microstructure evolution of as-cast Al-8.8 Mg-9.2 Si, Al-12.6 Mg-7.4 Si and Al-15.4 Mg-9.8 Si with different calculated Mg2Si content in the ferrous mold were studied by optical microscope（OM）and scanning electron microscope（SEM）. The results show that the solidification path of the three alloys are L→L1+Mg2Si→L2+Mg2Si+（Al+Mg2Si）binary eutectic→Mg2Si+（Al+Mg2Si）binary eutectic+（Al+Mg2Si+Si）ternary eutectic. The solidification microstructure at room temperature is composed of a certain amount of primary Mg2Si phase, binary eutectic and ternary eutectic clusters. With increasing Si content and Mg content, the number of primary Mg2Si phase increases, its growth morphology changes from octahedral polygon to dendritic with more developed secondary dendritic walls, but the morphology of the eutectic Mg2Si phase did not change significantly. The solidification microstructure morphology of Al-12.6 Mg-7.4 Si and Al-15.4 Mg-9.8 Si alloys was compared and it was found that the cumulative value of the aspect ratio of eutectic cells decreased with the increase of Mg2Si content. [ABSTRACT FROM AUTHOR]

A novel biomaterial Ti-17Mo (mass%) was designed for orthopedic implant applications. Hot working behavior and deformation characteristics were studied in the β-single structure by hot compression tests in the strain rate range 0.01–10 s−1 and temperature range 1123–1273 K using a Thermec Master-Z simulator. The microstructural evolutions of the deformed alloy were studied by a scanning electron microscope equipped with an electron backscattered diffraction detector. The microstructures of the hot deformed alloy showed that dynamic recovery was more active than dynamic recrystallization (DRX). However, partial discontinuous DRX by grain boundary bulging is activated at high temperatures and low strain rates, e.g., 1273 K and 0.01 s−1. Due to the high stacking fault energy of the β phase with a bcc structure, the Ti-17Mo alloy possessed comparatively low activation energy of hot deformation (283 kJ/mol) compared with the conventional Ti alloys bearing multiple alloying elements. [ABSTRACT FROM AUTHOR]

Recently, metastable β‐type Ti alloys have attracted attention as promising materials for medical implants due to low Young's modulus and superior biocompatibility. The former is dependent on texture developed during the thermomechanical process. Herein, new Ti–Zr–Nb–Sn–Mo alloys with ultralow Young's modulus and excellent biocompatibility are developed as promising materials for medical implants. The effect of Mo on the microstructure and mechanical properties of the Ti–18Zr–5Nb–3Sn system is investigated. X‐ray diffraction (XRD) and scanning electron microscope (SEM) results reveal that Mo acts as a β‐phase stabilizer. Moreover, mechanical behavior and recrystallization texture show strong composition dependence; the 2.5Mo alloy shows the lowest Young's modulus of 40 GPa. This is due to the formation of a recrystallization texture with strong Goss component of <001>. Corrosion behavior of the 2.5Mo alloy in the cell culture medium is similar to that of the commercially pure titanium (cp‐Ti), suggesting excellent corrosion resistance in the biological environment. Both murine fibroblasts and osteoblastic cells show good growth on the 2.5Mo alloy as the same level of that on the cp‐Ti. Implantation into rat subcutaneous tissue confirms no significant difference in the tissue reaction between the 2.5Mo alloy and the cp‐Ti. [ABSTRACT FROM AUTHOR]

Liquid metallurgy method based aluminum matrix composites (AMCs) are extensively utilized in diverse engineering applications including shipbuilding, structural, nonstructural, automotive, and aerospace owing to their superior strength, weightless, low density, excellent corrosion, and wear resistance. In the present investigation, liquid state technique was employed to prepare the LM4/aluminum nitride (AlN) composites containing four different mass proportion of AlN filler particles content. The weight proportion of filler particles from 0 to 12 wt% at 4 wt% intervals. Scanning electron microscope (SEM) images demonstrated a even dispersal of filler particles in the matrix. The test outcomes discovered that the LM4/12 wt% AlN AMCs had revealed extreme hardness, tensile, compression strength than the nonreinforced base matrix alloy. A considerable enrichment in the tensile strength is associated with the incorporation of AlN particles into LM4 matrix. The manufactured composites reveal high mechanical properties when compared with the alloy without reinforcement. The improvement of those lightweight AMCs with superior mechanical characteristics has a extreme potential to be employed for aircraft, structural and automobile applications. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia 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.)

In this study, Mg-xAl-3Zn alloys (x=0.5-1-2-3 wt.%) were produced by the permanent mold casting method. Microstructural characterization of alloys was done with the help of optical microscope (OM) and scanning electron microscope with energy-dispersive spectroscopy (SEM/EDS). Dry and bio-corrosive wear behaviors of alloys were investigated comparatively. Depending on the amount of Al in the alloys, the intermetallic phases were differentiated. Mg17Al12 phase was only observed in Mg-3Al-3Zn alloy distributed along the grain boundary as a continuous or semicontinuous network. The Mg-3Al-3Zn alloy hardness value was about 61.60±4.23 HV and approximately 30% higher than the other alloys. Dry wear and bio-corrosive (in simulated body fluid (SBF)) wear performances of the alloys were also compared. The abrasive wear mechanism was evident in dry ambient wear due to the intermetallic phases in the structure. Still, the liquid's lubrication effect is much more dominant in the bio-corrosive wear tests carried out in SBF. While Mg-3Al-3Zn wear rate was the lowest in dry wear, it was determined to be the highest in bio-corrosive wear for all applied load conditions. It had been understood that a large amount of Mg17Al12 phase in the structure caused such a result. [ABSTRACT FROM AUTHOR]

The aluminium alloy will improve its strength further with addition of reinforcement on considering its applications to produce much lighter weight to high strength parts. This work examines the addition of silicon carbide at varying levels of 12%, 14% and 16% in 6061 aluminium alloy. In addition, magnesium and copper are added to aid the strength of the Aluminium Metal Matrix Composite. The process parameters are optimized for the wear rate of the composites through Taguchi technique together with design of experiments. The percentage of SiC addition, load applied (30N, 60N and 90N) and sliding distance (500m, 1000m and 1500m) are the parameters taken into consideration for this wear analysis. It was observed that sliding distance was the most influencing factor, among others, while investigating the wear behaviour with ANOVA. Microstructure analysis performed with a scanning electron microscope on worn surfaces shows that SiC particles influence the wear rate of the composites. [ABSTRACT FROM AUTHOR]

A new generation of Ti-xNb-3Fe-9Zr (x = 15 , 20, 25, 30, 35 wt %) alloys have been designed using various theoretical approaches including DV-xα cluster, molybdenum equivalency, and electron to atom ratio. Afterward, designed alloys are fabricated using cold crucible levitation melting technique. The microstructure and mechanical performances of newly designed alloys are characterized in this work using scanning electron microscope and universal testing machine, respectively. Each alloy demonstrates monolithic β phase except Ti-35Nb-3Fe-9Zr alloy which display dual α ″ + β phases. Typically, niobium acts as an isomorphous beta stabilizer. However, in this work, formation of martensitic α ″ phases occurs at 35 wt % of niobium among the series of newly designed alloys. Furthermore, none of the alloys fail till the maximum load capacity of machine, i.e., 100 KN except Ti-35Nb-3Fe-9Zr alloy. Moreover, the Vickers hardness test is carried out on Ti-xNb-3Fe-9Zr alloys which demonstrate slip bands around the indentation for each alloy. Notably, the deformation bands and cracks around the indentations of each alloy have been observed using optical microscopy; Ti-35Nb-3Fe-9Zr demonstrates some cracks along with slip bands around its indentation. The Ti-25Nb-3Fe-9Zr alloy shows the highest yield strength of 1043 ± 20 MPa , large plasticity of 32 ± 0.5 % , and adequate hardness of 152 ± 3.90 Hv among the investigated alloys. The Ti-25Nb-3Fe-9Zr alloy demonstrates good blend of strength and malleability. Therefore, Ti-25Nb-3Fe-9Zr can be used effectively for the biomedical applications. [ABSTRACT FROM AUTHOR]

The beryllium bronze guide sleeve and the aluminum alloy valve body are assembled to form a beryllium bronze-aluminum alloy stepped hole which requires multiple positioning and tool changes during machining, resulting in lower machining efficiency and accuracy. The geometry error and surface quality of beryllium bronze-aluminum alloy stepped holes after reaming were studied in this research. The geometric error (cylindricity, concentricity and verticality) and diameters of the stepped holes were measured by using a three-coordinate measuring machine. The experimental results show that the PCD forming cutters has high geometric error and diameter stability when reaming beryllium bronze-aluminum alloy stepped holes. Under various cutting parameters, the cylindricity of stepped holes was guaranteed to be within 6μm, and the concentricity of stepped holes was guaranteed to be within 6μm, and verticality of stepped holes was guaranteed to be within 2μm. With the increase of spindle speed and feed per tooth, the diameters of beryllium bronze holes increase while the diameters of aluminum alloy holes decrease and then increase. As the cutting allowance increases, the diameters of the beryllium bronze holes and aluminum alloy holes decrease. The laser confocal microscope and scanning electron microscope were used to detect and analyze the surface quality of beryllium bronze-aluminum alloy stepped holes after reaming. The experimental results show that the surface roughness of the beryllium bronze-aluminum alloy stepped holes reamed by using the PCD forming cutter were less than 0.3μm, and the surface roughness of the beryllium holes were slightly larger than the aluminum holes. The fourth group of experimental parameters (spindle speed 1290r/min, feed per tooth 0.01mm/z, cutting allowance 0.06mm) was selected as the actual processing parameters. There are cavities on the surface of the initial stepped holes before reaming and the cavities basically disappear after reaming, so the surface quality of the beryllium bronze-aluminum alloy stepped holes has been greatly improved. [ABSTRACT FROM AUTHOR]

Applications at elevated temperature require alloys that can form a protective oxide layer, and Cr and Si are known to form these layers, allowing FeCrSi alloys to be oxidation resistant. However, few studies have considered Si content higher than 2 wt.%. The objective here was to analyze the cyclic oxidation resistance of innovative FeSiCrNi alloys with different Si and Cr contents (around 5 wt.% of both). Cyclic oxidation tests were performed on three alloys at 950 °C in still air. The microstructure of the cast and heat-treated alloys and the oxide scales formed were analyzed by scanning electron microscope and energy-dispersive X-ray spectroscopy. Oxide layers were also characterized by X-ray diffraction. Comparing silicon contents of 4.65 and 5.9 wt.% in two different alloys containing around 4 wt.% chromium and 0.8 wt.% carbon, it was demonstrated that the lower silicon content was not enough to avoid iron oxides formation and continuous spallation. On the other hand, the higher silicon alloy exhibited low mass gains and a protective oxide layer composed of Cr2O3 and MnCr2O4, with some enrichment of silicon at metal/oxide interface. A third alloy, containing 2.7 wt.% carbon and, thus, graphite in its microstructure suffered decarburization in some regions, although in other regions it formed a protective oxide even in an alloy containing 3.25 wt% Cr and 6.6 wt.% Si. These results demonstrate that it is possible to have a high-temperature resistant alloy with low Cr content relative to conventional alloys by using high Si additions. [ABSTRACT FROM AUTHOR]

This paper details the synthesis of Al7475 alloy with 8% wt. of nano B4C particulate metal matrix composites using the liquid metallurgy technique. Scanning electron microscope (SEM) of the synthesized composites demonstrates the uniform dispersion of the reinforced nano B4C particles throughout the matrix. EDS spectrums confirmed the various elements present in Al7475-B4C composites. Hardness, tensile and compression tests were carried out to find out the impact of nano B4C on various mechanical properties of the composites. Synthesized composites had a greater hardness, tensile and compression strength with the incorporation of B4C particles. Tensile failure analysis was studied using SEM images of fractured surfaces. [ABSTRACT FROM AUTHOR]

Streams of multimodal three-dimensional (3D) and four-dimensional (4D) data are revolutionizing our ability to design and predict the behavior of a broad array of advanced materials systems. Over the last 10 years, a new 3D imaging platform consisting of a femtosecond (fs) pulsed laser coupled with a focused ion beam scanning electron microscope (FIB SEM) has been developed by UC Santa Barbara in collaboration with Thermo Fisher Scientific (formerly FEI). The femtosecond-laser-enabled FIB SEM, called the TriBeam, has become one of the only 3D serial sectioning methods available that can gather millimeter-scaled multimodal datasets at sub- μ m voxel resolutions; these length scales are critical for many materials problems. Multimodal chemical, crystallographic, and morphological information can be gathered rapidly on a layer-by-layer basis and reconstructed in 3D. Large (gigabyte to terabyte scale) 3D datasets have been generated for a broad array of materials systems, including metallic alloys, ceramics, biomaterials, polymer- and ceramic-matrix composites, and semiconductors. The research tasks performed have resulted in a completely new design, operating with a dual-wavelength femtosecond-pulsed laser on a plasma focused ion beam (PFIB) platform. [ABSTRACT FROM AUTHOR]

Thermite reduction as one of the most promising methods for preparation of TiAl alloy, the metal-slag separation behavior in the whole process of chemical reaction, including both the alloy components and slags to be removed, is still ambiguous. In this paper, the two-step nucleation mechanism was applied to investigate the metal-slag separation behavior in the thermite reduction process for the preparation of TiAl alloy, which was confirmed by thermodynamic calculation based on density functional theory. Moreover, the component of products acquired from thermite reaction was characterized and analyzed by x-ray diffractometer, scanning electron microscope and transmission electron microscope, respectively. According to the results of the experiment and calculation, the formation and separation mechanism between alloy and slag in the process of preparing TiAl alloy via thermite reduction is visualized, which is universal in the whole metallurgical procedure involving redox and slag-making process. [ABSTRACT FROM AUTHOR]

To obtain higher electrical conductivity and lower area specific resistance (ASR), the 10% Fe doped Ni–Co (NCF) alloy was prepared on SUS 430 steel substrate by electroplating for solid oxide fuel cells (SOFCs) interconnects application. Then, the SUS 430 steels and NCF coated steels were oxidized at 800 °C. The microstructure and oxide phase of samples were tested by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). These results proved that the NCF coated steel achieved the lower oxidation rate of 9.28 × 10−14 g2cm−4s−1 and ASR of 14.72 mΩ cm2. • Fe doped Ni–Co coatings were electroplated on SUS 430 stainless steel. • The multi-layers oxides were thermally converted from alloy coatings. • The growth of Cr 2 O 3 oxide layer was restrained. • The high electrical conductivity were exhibited. [ABSTRACT FROM AUTHOR]

The effects of Mg on microstructure, defects and properties of Al–Si alloy deposited by Wire and Arc-based Additive Manufacturing (WAAM) were investigated. The WAAM alloys were characterised by the metallographic microscope, X-ray diffraction, scanning electron microscope, computed tomography and electronic universal testing machine. The results show that the secondary dendrite arm spacing (SDAS) and hydrogen content of as-deposited WAAM alloy increase, and the tendency of pore formation increases with an increase in Mg content. The impurity Fe in the WAAM alloy with low Mg content is mainly in β-Fe phase, while with high Mg content is mainly in the π-Fe phase. After solution treating and ageing treatment (T6 heat-treat), the microstructure of WAAM alloy tends to be uniform. With the increase of Mg content, the size of eutectic silicon particles increases gradually. Furthermore, the UTS and YS of the alloys increased, and the elongation decreased. [ABSTRACT FROM AUTHOR]

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office 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.)

Influence of Equal Channel Angular Pressing on mechanical properties and fracture toughness of Al-Zn alloy were studied in present investigation. Samples are successfully processed using the ECAP technique for up to a four passes by using route A. Al-Zn alloys were heated to a solid solution treatment temperature at 550 °C for 2 h prior to ECAP, this treatment introduces the precipitates which were capable of obstructing motions of dislocation and improves the refinement of the grain during ECAP process Finally, artificial aging was performed at a temperature of 190 °C for 0-20 hours with an interval of 2 h and specimens were cooled at room temperature with natural air. Fracture toughness was found experimentally for ECAP processed samples using SE (B) specimens according to ASTM E399 standard. This study revealed the enhancement in mechanical properties such as yield strength, ultimate strength and microhardness after four passes by route A technique. The improvement in the fracture toughness properties of artificially aged ECAP samples can also be due to dislocation strengthening, grain boundary strengthening, and the creation of much finer UFG grains, according to the results. Despite the increased tensile strength after ECAP, the ductility behavior has decreased due to the precipitation of GP zones and dispersion of η, ή, T and E within the Aluminum matrix, Furthermore, scanning electron microscope (SEM) micrographs revealed that ductile fracture with large dimples occurred in the artificial aged samples after the ECAP procedure. [ABSTRACT FROM AUTHOR]

Corrosion rates of ideal Mg alloys used for sealing tools in petroleum industry should be able to be altered to adapt to different downhole environments, and corresponding mechanisms of modified corrosion rates need to be clarified. In this study, annealing treatments were carried out at 400 or 450 °C for 2 h to tune the microstructures and corrosion rates of Mg-2Gd-xCu (x = 0, 0.5 and 1 wt.%). Microstructures were characterized by scanning electron microscope, X-ray diffractometer and electron backscatter diffraction while corrosion behaviors were investigated by immersion and electrochemical tests. The results showed that after annealing, the growth in the average second phase size and the average grain size, the weakened basal texture and the eliminated residual stress contributed to reduced corrosion rates. As a result, corrosion rates of Mg-2Gd-0.5Cu and Mg-2Gd-1Cu decreased obviously but were still higher than 30 mm·y-1 after annealing, the recommended minimum corrosion rates. It proved that a gradient of corrosion rates of Mg-Gd-Cu can be achieved through annealing treatment, which were beneficial to further application of Mg-Gd-Cu in the field of oil and gas exploitation. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia 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.)

Copyright of International Journal of Computerized Dentistry is the property of Quintessence Publishing Company Inc. 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.)

In this study, the machining characteristics of pulse short arc milling (SEAM) Ti6Al4V alloy were studied. In this regard, the influence of SEAM parameters on the material removal rate (MRR), relative electrode wear ratio (REWR), and surface integrity of Ti6Al4V is studied. A wide variety of processing parameters, including different voltages, frequencies, duty cycles, flushing pressures, electrode rotation speeds, and electrode feed rates, are considered in the investigation. Scanning electron microscope (SEM), energy dispersive spectrograph (EDS), and micro-hardness analysis are applied to analyze results. Moreover, a multichannel data acquisition system is used to measure gap voltage and gap current. Obtained results cover the variation of MRR, REWR, surface roughness (Ra), average resolidified layer thickness, and average heat-affected zone thickness with different processing parameters. Furthermore, the electrode surface morphology and chemical composition of the negative growth of REWR are studied. Based on the obtained results, the microstructure of the resolidified layer and heat-affected zone of the workpiece cross-section is confirmed. This study provides a basis for the high-quality pulse SEAM technology of difficult-to-machine (DTM) materials to enter the semi-finishing field. [ABSTRACT FROM AUTHOR]

Alumnium alloy LM 25 based composites reinforced with boron carbide at different weight fractions of 4%, 8%, and 12% were fabricated by stir casting technique. The microstructures and morphology of the fabricated composites were studied by scanning electron microscopy and energy dispersive spectroscopy. Elemental mapping of all fabricated composites were done to demonstrate the elements present in the matrix and fabricated composites. The results of microstructural analyses reveal homogenous dispersion of reinforcement particles in the matrix with some little amount of clustering found in composites reinforced with 12% wt. of boron carbide. The mechanical characterization is done for both alloy LM 25 and all fabricated composites based on hardness and tensile strength. The hardness increased from 13.6% to 21.31% and tensile strength 6.4% to 22.8% as reinforcement percentage of boron carbide particles increased from 0% to 12% wt. A fractured surface mapping was also done for all composites. [ABSTRACT FROM AUTHOR]

In this study, the paint layer was removed on the surface of 5083 aluminum alloy using laser cleaning and mechanical grinding. The microstructure and performance of experimental samples were carefully investigated using scanning electron microscope, energy disperse spectroscopy and other methodologies. The results showed that compared with mechanical grinding, laser cleaning can improve the surface paint coating of aluminum alloy more effectively. The surface of the matrix formed uniformly distributed volcanic craters and small holes emerged at the spot junction after laser cleaning. The carbon and oxygen content on the substrate surface after laser cleaning was much lower than that after mechanical grinding. In addition, the corrosion resistance and coating adhesion of the substrate were obviously improved using laser cleaning. It was closely associated with refinement of the grains and reduction in surface roughness. We concluded that laser cleaning can be widely used to replace mechanical grinding in manufacturing on the premise of meeting industrial needs. [ABSTRACT FROM AUTHOR]

Exploring novel materials with large magnetocaloric effect and excellent mechanical properties near room temperature (RT) are highly desired for Ni-Mn based Heusler alloys. In this work, the martensitic transformation, magnetic properties, and mechanical properties of Ni50-xCoxMn50-yTiy (x = 13–15, y = 13–16) alloys were systematically investigated by tuning Co or Ti contents. The magnetism of austenite was enhanced with an increase in Co or Ti content. 5M and 6M martensites were observed in Ni-Co-Mn-Ti alloys by transmission electron microscopy. The Ni36Co14Mn35Ti15 alloy with a large magnetocaloric effect was found near room temperature by tuning composition. The largest magnetization change (ΔM) and magnetic entropy change (ΔSm) in the Ni36Co14Mn35Ti15 non-textured polycrystalline alloy obtained during martensitic transformation under the magnetic field of 5 T were about 106 emu/g and 19.3 J kg−1 K−1, respectively. Furthermore, the maximum compressive strength and ductility for the Ni36Co14Mn35Ti15 as-cast alloy can exceed 1220 MPa and 15%, respectively. The fracture mechanism and bonding interaction were analyzed by a scanning electron microscope and first-principles calculations. [ABSTRACT FROM AUTHOR]

Nowadays, the Wire Electrical Discharge Machining (WEDM) process was also working to cut the hard titanium alloys. During the WEDM, the generation of high temperatures was used to melt and vaporize and also flushed away the hard titanium alloy. The tough Ti–6Al–2Sn–4Zr–2Mo alloy was machined in the current research by the WEDM method and machining features such as surface roughness (SR) and Material Removal Rate (MRR) were statistically evaluated to achieve optimum performance. The investigations were performed using the Taguchi orthogonal array technique. The optimum process factors were defined from the main effect plot 32 μs, 3 m/min, and 12 g for material removal rate and as 10 μs, 32 μs, 7 m/min, and 12 g for surface roughness. The best essential parameters were established from the Analysis of variance (ANOVA) analysis. The pulse on-time current and pulse off time were identified as important parameters for the material removal rate with a contribution of 23.60%, 5.91%, and 65.02%. The best essential parameters for surface roughness were pulse on time, pulse off time, and a combination of pulse on-time and pulse off time with a percentage contribution of 22.71% and 36.88% respectively.Moreover, the machined surface was examined using the Scanning Electron Microscope (SEM). [ABSTRACT FROM AUTHOR]

Information of solidification processes, liquidus temperatures, and phase relationship of the Mg-Mn-Y system in the Mg-rich corner was systematically studied using differential scanning calorimetry (DSC) measurement, x-ray diffraction (XRD) analysis and scanning electron microscope (SEM) analysis. One single-phase region (Hcp), two two-phase-equilibrium regions (Hcp + Cbcc & Hcp + Mg24Y5), and one three-phase-equilibrium region (Hcp + Cbcc + Mg24Y5) were identified in the Mg-rich corner at 550 °C in this work. No ternary phase was observed within the currently studying composition range. Corresponding calculations using the current available thermodynamic description of the Mg-Mn-Y system for the comparison with experimental results were performed. The experimental and calculation results show certain deviations in the phase transition temperatures and the tie-lines of the equilibrium phase regions. The differences are attributed to the extreme low concertation of alloying elements alloyed in Mg in this work, where few studies were performed in literature and nevertheless included in the previous assessment work. Therefore, the current results could provide an essential basis for the further study and revision of the thermodynamic description of the Mg-Mn-Y system and the design/development of new alloy and process of Mg-Mn-Y based alloys. [ABSTRACT FROM AUTHOR]

Element substitution is an efficient method to enhance the activation property of TiFe alloys. In this paper, Zr, Mn and Ni were utilized to replace Fe in the alloy partially, and different content rare earth Sm substitute Ti in the alloy. The alloys with nominal compositions of Ti 1.1- x Fe 0.6 Ni 0.1 Zr 0.1 Mn 0.2 Sm x (x = 0–0.08) were made through vacuum induction melting. The microstructure, composition and hydrogen storage property of alloys were measured in detail by X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy and automatically Sievert apparatus. The results reveal that the as-cast alloys contain TiFe as major phase and Ti 2 Fe as secondary phase. Sm addition refines the grain of alloys obviously. All alloys have good activation properties and can be completely activated without any heat treatment. The activation performance can be further improved by partially replacing Ti with Sm, and the incubation period of activation can be shortened greatly. • Sm addition refines the grains of TiFe-based alloys. • The activation property of alloys can be improved obviously after adding Sm. • Introducing Sm improves the hydrogen storage kinetics of samples. • The hydrogen absorption and desorption hysteresis reduces after adding Sm. [ABSTRACT FROM AUTHOR]

AZ61 magnesium alloy metal matrix composites (MMCs) with different weight percentages (0, 1 and 2) of micro-silicon carbide particles (SiCp) were fabricated using stir casting method. Effects of SiCp on the microstructural distributions, mechanical and fatigue properties, and fracture surfaces have been investigated. The microstructural observations of as-cast MMCs unveil the existence of primary α-Mg phase and the presence of large amount of β-Mg17Al12 secondary phase at grain boundary. The specimens are subjected to homogenization heat treatment at 410 °C for 24 h; the β-Mg17Al12 phases are significantly dissolved in the matrix grain boundaries which enhance the ductility and decrease the hardness compared with the as-cast materials. The addition of SiCp reinforcement led to improved yield strength (YS) and ultimate tensile strength (UTS) of AZ61/SiCp composite compared to the unreinforced alloy. The maximum values of YS and UTS have been attained at AZ61/1wt%SiCp composites. The enhancement of YS and UTS was due to the presence of a uniformly distributed reinforced SiCp, which depends on grain refinement of the matrix and strong interfacial bonding between the matrix and reinforcement. In the case of fatigue test results, the addition of SiCp reduced the fatigue life and strength of AZ61 alloy composite. However, addition of 1wt%SiCp showed good mechanical and fatigue properties compared to pure AZ61 magnesium alloy and AZ61/2wt%SiCp composite. Furthermore, the effects of addition of SiCp on the mechanical and fatigue properties of the composite were confirmed by using the scanning electron microscope observation of fracture surfaces. [ABSTRACT FROM AUTHOR]

The current study explores the effect of Overalloyed filler wire (ERNiCrMo-17) on the weldments of alloy C-276 fabricated through pulsed current tungsten inert gas welding (PCTIG) and tungsten inert gas welding (TIG) technique. The optical microstructure shows that current pulsing technique obtained the refined equiaxed microstructure compared to TIG coarse cellular structure. From Scanning electron microscope (SEM), it is identified that secondary precipitates are absent in the boundary zones of the weld zone. Energy dispersive spectroscopy (EDS) confirmed that microsegregations were absent in between the grain and boundary regions. The results of the tensile test verified that fracture was occurred in the base metal, not in the fusion zone. [ABSTRACT FROM AUTHOR]

In this study, we conducted a quantitative evaluation of dislocation density by scanning electron microscopy electron channeling contrast imaging for α grains of a Ti-6Al-4V alloy deformed at room temperature. The depth of visibility of dislocations is experimentally measured as 140 to 160 nm by a serial sectioning observation. This result is compared with the theoretical value and applied to evaluate dislocation density. These factors confirm that the theoretically calculated value of the depth of visibility, at 5 to 6 times the extinction distance, is valid for the hexagonal close-packed Ti alloy. [ABSTRACT FROM AUTHOR]

Zirconium was one of the rare earth materials. In this paper, the effect of Zr additions in the microstructure, mechanical and in vitro properties were investigated. The phases present in the alloy were identified by X-ray diffraction analysis. The presence of the added alloying elements was confirmed with Energy Dispersive X-ray spectroscopy. The surface morphology and the proper mixing of the element were analyzed using a scanning electron microscope. The mechanical proopeties were analyzed and show that the material has good compressive strength and tensile strength. The hardness of the material increases due to Zr additions. The alloys show improved and slow degradation of the material in simulated body fluid analyzed using a potentiostat. The alloy can be suggested for biomedical implants due to its higher mechanical properties and slower degradation rate. [ABSTRACT FROM AUTHOR]

In this paper, a unified viscoplastic constitutive model for Ti–6Al–4V alloy coupling with damage and softening mechanisms was established to predict the flow behaviors and damage evolution in hot tensile process. To obtain the flow behaviors of Ti–6Al–4V alloy, the hot tensile tests were performed at temperatures between 750 °C and 850 °C and strain rates of 0.01–1 s−1. Then the evolution of microstructure was investigated by scanning electron microscope (SEM) under hot tensile conditions. Otherwise, the macro-fracture morphology of the tensile specimen was observed by SEM. The flow stress and microstructure evolution were predicted based on the set of constitutive model. The constitutive model was embed in ABAQUS by coding a user-defined material subroutine. The results show that the flow stress increases with the temperature decreasing and the strain rate increasing. By comparing the experimental and calculated results, the flow stress and damage evolution can be accurately predicted by the constitutive model. The fracture due to damage can be well predicted by the simulation model, indicating the good predictability of the constitutive model. [ABSTRACT FROM AUTHOR]

Corrosion and wear failures are bottlenecks for restricting applications and developments of Al‐based functional materials. As a new lubrication technology, superhydrophobic preparation provides an effective way to settle Al alloy corrosion. The preparation methods of superhydrophobic Al alloys are mainly multistep strategies. In this study, superhydrophobic Al alloy, has been prepared by an efficient one‐step electrochemical etching process. Meanwhile, its micromorphology has been observed by a scanning electron microscope. The wettability has been measured by video optical contact angle meter. The corrosion behavior has been tested by electrochemical workstation, and wear performance has been characterized by friction tester. The results show that the micro‐nanoterraced concave–convex structure has been fabricated and an as‐prepared surface exhibits excellent superhydrophobic behavior. Further electrochemical and tribological tests show that corrosion resistance and wear resistance have also been significantly improved. This study provides a new method to prepare wear‐resistant and corrosion‐resistant Al alloy for widening applications of multifunctional Al‐based engineering materials. [ABSTRACT FROM AUTHOR]

Alloys strengthened by nanometer-sized Laves phases have been used as structural components working in corrosive environments at high temperatures owing to the favorable physical and chemical properties of Laves phases. However, due to the small sizes of Laves phases in alloys, their precise characterization cannot be realized efficiently by the existing methods. We previously found that under irradiation of a polished Zircaloy-4 alloy [Zr–1.50Sn–0.25Fe–0.15Cr (wt.%)] with a focused, low-energy (30 keV) electron beam, surface Zr atoms in the α-phase matrix, instead of the ones in nanometer-sized Zr(Fe, Cr)2 Laves phases, were able to undergo significant sputtering into vacuum in a field-emission scanning electron microscope (FE-SEM), resulting in the exposure of the Laves-phase nanoparticles (NPs). Based on this surprising physical phenomenon, here we successfully develop a methodology for performing statistical characterization of Laves-phase NPs in fully recrystallized Zircaloy-4 alloys as well as their partially recrystallized counterparts. By comparing the attributes of the Laves-phase NPs in both partially and fully recrystallized alloys, the conventional, tiny Ostwald ripening of the Laves phases was, for the first time, found to occur during the alloy recrystallization process. These understandings are likely to elucidate the universal mechanisms underlying the nucleation and growth of Laves-phase NPs in solid solutions. [ABSTRACT FROM AUTHOR]

To obtain a robust diffusion-bonded joint at a relatively low temperature, Nb foil was applied as an interlayer to the diffusion bonding of Zr-4 alloy, and a wide process parameter involving the bonding temperature of 720–820 °C and holding time of 30–120 min was investigated to reveal the evolution of interfacial structure and mechanical properties of the joints. The β-(Zr, Nb) and Widmanstädter microstructure formed at the interface induced by the eutectoid transformation of the diffused Zr and Nb at the bonding temperatures over 740 °C. The phase structure and the thickness of β-(Zr, Nb) layer were not considerably influenced by the increase in diffusion parameters while the Widmanstädter zone thickened significantly. Moreover, the tensile strength and elongation of the resultant joints could be stabilized above 433 MPa and 7.8%, respectively, when the bonding temperature exceeded 760 °C with a holding time of 30 min. By extending the holding time to 60 min at 760 °C, the tensile strength and elongation could reach 454 MPa and 12.6%, respectively, comparable to those obtained at an elevated temperature of 820 °C for 30 min. Additionally, the samples fractured at the diffusion layer were characterized by the in-situ tensile test under the scanning electron microscope, and it was discovered that the crack initiation and propagation process occurred mainly between the β-(Zr, Nb) and Widmanstädter diffusion zone. • The well-bonded Zr-4 joints were achieved by the application of Nb interlayer. • The diffusion layer consisted of β-(Zr, Nb) and Widmanstädter microstructure. • The Nb addition lowered bonding temperature without weakening tensile properties. • The fracture occurred between the β-(Zr, Nb) and Widmanstädter diffusion zone. [ABSTRACT FROM AUTHOR]

Direct synthesis of TiAl alloys through magnesiothermic reduction of an intermediate TiAl2O5 phase was demonstrated at various temperatures and Mg/TiAl2O5 molar ratios. X-ray diffraction (XRD) results verified TiAl alloys could be directly synthesized at a Mg/TiAl2O5 molar ratio of 25 at 900 °C. At lower Mg/TiAl2O5 molar ratios of 12.5 and 5, the desired TiAl alloys underwent a transition from the TiAl alloy to the TiAl2 alloy. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis indicated that a dense Al2O3 film could be easily generated on the surface of the TiAl alloy preventing further oxidation of TiAl alloys. The by-products from the magnesiothermic reduction mainly consisted of MgAl2O4 spinel, which could not be separated from the metallic alloys with a solution of diluted HCl and HNO3 but could be partially separated by particle size. Particle size screening suggested that particles larger than 45 μm mainly contained MgAl2O4 spinel-based by-products and particle size below 45 μm consisted of a mixture of TiAl2 alloys and MgAl2O4 spinel-based by-products. [ABSTRACT FROM AUTHOR]

A hybrid composite material was obtained by stacking carbon fiber reinforced plastic (CFRP) onto 7075‐W Al alloy sheet. Mechanical properties of the CFRP/Al hybrid composite material were measured by tensile and flexural tests. To investigate the flow of the epoxy, the thinning was measured using an optical microscope and the defects were observed by a scanning electron microscope. A finite element model was established to predict the thickness and the contact pressure distributions of the CFRP/Al hybrid composite material during the forming process. The results showed that the tensile strength (TS) of the CFRP/Al hybrid composite was increased by 10% and the fracture strain was increased by 24% compared with the single 7075 Al alloy. The flexural strength (FS) and the displacement of the loading nose were improved by 13% and 75%, respectively. According to the microstructure observation, large cracks in the epoxy could be found on the side wall of the U shape part. The results of numerical analysis indicated that the low contact pressure at side wall was the main reason for the decrease of the tensile and FS and the delamination between laminates. [ABSTRACT FROM AUTHOR]

In this study, the effect of annealing treatment on microstructure and mechanical properties of the Nb-10Hf-1Ti wt.% produced by Spark Plasma Sintering (SPS) was investigated. Scanning electron microscope (SEM), optical microscopy, X-ray diffraction analysis, hardness, and uniaxial tension test were used to characterize the samples. Annealing treatment was carried out in a vacuum of 10-3 Pa at 1150 °C for 1, 3, 5, and 7 hours and in an argon atmosphere at 1350 °C for 5 hours. Internal oxidation and subsequent hafnium oxide formation causes the hardening of the C103 alloy and drastically increases the hardness and tensile strength. However, HfO2 particles formed at the grain boundary cause brittleness and cleavage fracture of samples. Volume fraction, particle size, and mean inter-particle spacing of oxides significantly change by annealing which affects the mechanical properties. The SPSed sample at 1500 °C is softened by annealing at 1150 C for 5 hours and its hardness and yield strength are reduced from 303 to 230 Hv and 538 to 490 MPa respectively. While annealing at 1350 °C for 5 hours increases hardness and yield strength increases to 343 Hv and 581 MPa respectively. [ABSTRACT FROM AUTHOR]

The quaternary light refractory high-entropy alloys of AlxCrTiMo were fabricated by spark plasma sintering method. Investigation of the oxidation kinetics behavior of the alloys with different Al content at 1000 °C shows varying degrees of weight gain, and the curve of the sample with low Al concentration expresses distinctly different variation tendency. Formation process of oxide layers was analyzed and microstructure and cross sections of distribution of elements were examined by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). TiO2 and Al2O3 phases were observed on the oxide film after exposure to air at 1000 °C for 1 h and 7 h time intervals. These experiments show that the Al-content in the alloy can promote the formation of Al2O3, and the equilibrium of the volatilization rate of the refractory elements as well as the formation rate of the oxidation protective layer determines the weight gain of the AlxCrTiMo. [ABSTRACT FROM AUTHOR]

The main focus of the present study is to compare the effect of different alloying elements on Al–Mg alloy foams. Al–Mg15–X10 (X = Cu, Zn and Si) alloy foams were produced via powder metallurgy route by using Mg as a blowing agent. Macro- and microstructural characterisations of the foams were performed using X-ray tomography, X-ray diffraction and scanning electron microscope. Corrosion studies such as weight loss measurement, hydrogen evolution method and potentiodynamic test were conducted. Mechanical properties were evaluated by subjecting the samples to quasi-static compression and microhardness tests. All the alloy foams showed a comparable structure. The Cu-containing foams exhibited the highest strength, while the Zn-containing foams showed the highest expansion. However, the other properties such as brittleness, elastic modulus and burning nature were found to be better for the Si-containing foams. [ABSTRACT FROM AUTHOR]

The laser nitriding was performed in nitrogen gas at room temperature (20 °C) and low temperature (−190 °C) by a low power fiber laser to modify the wear and abrasion resistance of NiTi alloy. The surface roughness and element composition were analyzed by roughness device and energy-dispersive X-ray spectroscopy respectively. The results of roughness show that laser treatment can change the surface roughness due to the laser remelting. The effect of laser nitriding on the microhardness, friction coefficient, and worn scars of NiTi alloy was also studied, which shows that the microhardness of the NiTi alloy increases after laser nitriding. The optical microscope and scanning electron microscope were used to characterize the surface of NiTi alloy after wear testing to observe the microstructure of worn scars. The results show that the laser nitriding with different parameters can induce a nitride layer with different thicknesses and the higher energy deposition is the key factor for the formation of the nitride layer, which can decrease the friction coefficient and reduce wear loss during the application of NiTi alloy. The improvement of wear resistance can be attributed to the hard nitriding layer. [ABSTRACT FROM AUTHOR]

The effects of different Sn additions (0, 0.5, 1.0, 2.0 and 3.0 wt%) on hot tearing susceptibility (HTS) of Mg–Zn–Zr alloy were studied using a "T-shaped" hot tearing mold in a pouring temperature of 700 °C and a mold temperature of 270 °C. The "Clyne–Davies" hot tearing prediction model and commercial simulation software, Procast, were used to characterize the HTS of alloys. The dendrite coherency temperature was obtained by means of differential thermal analysis. The phases evolution, microstructures and morphology of the crack zone of Mg–4Zn–xSn–0.6Zr alloys were investigated by using X-ray diffraction and scanning electron microscope. The experimental results show that the HTS of Mg–4Zn–xSn–0.6Zr alloys decreases with Sn additions up to 1.0 wt%, and then exhibits a slight increase with further Sn additions up to 3.0 wt%. The Sn additions into Mg–4Zn–0.6Zr alloy can form Mg2Sn phase with high melting point. Appropriate addition of Sn can refine grain size, decrease the dendrite coherency temperature, increase the thickness of liquid film and the feeding ability at the end of solidification, which reduce the HTS of the alloy. However, excessive Sn addition will make Mg2Sn aggregate and grow up, and hinder the residual liquid-phase feeding in the late solidification stage, resulting in an increase in HTS of the alloy. The order of HTS of studied alloys is: CSC(Mg–4Zn–0.6Zr) > CSC(Mg–4Zn–0.5Sn–0.6Zr) > CSC(Mg–4Zn–3Sn–0.6Zr) > CSC(Mg–4Zn–2Sn–0.6Zr) > CSC(Mg–4Zn–1Sn–0.6Zr). [ABSTRACT FROM AUTHOR]

Continuous research into critical functional property enhancement of materials employed in artificial intelligence systems is imperative to overcome performance limitations. This study investigated the thermal and mechanical properties of stir-cast fabricated Al-Cu alloy modified with addition of iron-millscale (IMS) particles varied from 2-6 wt.%. The alloys microstructure was analysed using both optical and scanning electron microscope coupled with energy dispersive spectroscopy (SEM/EDS). PerkinElmer Thermogravimetry/Derivative thermal analyser was used to assess the alloys thermal characteristics while the mechanical properties were evaluated using relevant state of the art equipment. Results show that the best thermal and mechanical properties comparable to established standards were achieved at 6 wt.% IMS particle addition. Contributions to the alloy enhanced performances stemmed from the structure refining propensity of IMS particles. Based on the thermal and mechanical properties demonstrated, the alloy is recommended for application in pneumatic offshore valve actuator used in oil and gas flow process lines. [ABSTRACT FROM AUTHOR]