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In this paper, the microstructure and mechanical properties of Al-6.5Si-5.5Cu-0.2Zr-0.01Sr-0.06Ti-0.2Ce cast aluminum alloys were investigated in multistage solid solution systems. The microstructure of the alloy was characterized using an optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), x-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The hardness and conductivity of the alloy were measured using a Vickers hardness and eddy current conductivity testers, respectively, and the tensile properties were described by a drawing machine. The results showed that the mechanical properties of the alloy are the worst under the four-stage solid solution system (G1). With the increase in multistage solution temperature and holding time, θ phase (Al2Cu) was gradually dissolved into α-Al matrix to enhance the effect of dislocation strengthening. When the solution temperature reached 510 °C, the mechanical properties of the alloy were the best, and the tensile strength and elongation were increased to 354.90 MPa and 9.02%, respectively. With the increase in temperature, eutectic Si agglomeration and large area of insoluble phase between metals were found, resulting in the decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

Micron‐sized graphite particles additions to Al2011 alloy were investigated to know their impact on mechanical properties. The stir cast method was used to manufacture the Al2011 alloy with 2 and 4 wt% of graphite particles reinforced composites. The microstructural analysis and mechanical properties of the synthesized composites were tested. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) spectrums were used to characterize the microstructure of the samples that were obtained from the casting. SEM micrographs indicated the homogeneous distribution of particles and the EDS patterns confirmed the presence of graphite particles. Al2011 alloy hardness was decreased with the addition of graphite particles. Further, with the addition of 2 and 4 wt% of graphite particles in the Al2011 alloy, the ultimate tensile and yield strengths of composites were increased with increase in elongation. SEM micrographs of tensile fractured surfaces were used to study the various fractured behaviors in the Al2011 alloy‐graphite composites. [ABSTRACT FROM AUTHOR]

Due to the poor activation performance and kinetics of Ti50V25Cr25 alloys, the element Zr was added to improve the phase structure of the alloy and achieve a high-performance hydrogen storage alloy. The Ti50−xV25Cr25Zrx (x = 0, 5, 7, and 9) system alloys were prepared by arc melting. The alloys were analyzed using an X-ray diffractometer (XRD), scanning electron microscope (SEM), and differential scanning calorimeter (DSC). The hydrogen storage capabilities of the alloys were also obtained by the Sievert volumetric method. The results indicated that the alloy with Zr added had a combination of the C15 Laves phase and the BCC phase, whereas the Zr-free alloy had a BCC single phase. The partial replacement of Zr with Ti resulted in an increase in the lattice parameters of the main phase. The hydrogen storage kinetic performance and activation of the alloys both significantly improved with an increasing Zr concentration. The time to reach 90% of the maximum hydrogen storage capacity decreased to 2946 s, 230 s, and 120 s, respectively, with the increases in Zr concentration. The initial hydrogen absorption content of the alloys increased and then decreased after the addition of the element Zr. The second phase expanded with an increasing Zr concentration, which in turn decreased the abundance of the BCC main phase. The Ti43V25Cr25Zr7 alloy showed good cycle stability and hydrogen-desorption performance, and it could absorb 90% of the maximum hydrogen storage capacity in around 230 s. The maximum hydrogen-absorption capacity of the alloy was 2.7 wt%. The diffusion activation energy of hydrogen desorption dropped from 102.67 kJ/mol to 92.62 kJ/mol. [ABSTRACT FROM AUTHOR]

In the present paper, microstructural changes in two alloys, IN617 and DMV617 mod, after 5 h and 1000 h of aging at 700 °C were investigated using scanning transmission electron microscopy. The mechanical properties of the samples were evaluated using hardness tests. Precipitates were identified using energy-dispersive X-ray spectroscopy analysis. After long-term aging, intensive precipitation of the M23C6 carbides and γ′ intermetallic phase in the microstructure of alloys was observed. In the IN617 alloy, continuous layers of M23C6 carbides along the grain boundaries after long-term aging were observed. The minor addition of boron to the DMV617 mod alloy is advantageous in microstructure formation during long-term aging because it decreases the agglomeration of M23C6 at the grain boundaries. [ABSTRACT FROM AUTHOR]

The deformation aspects associated with the micro-mechanical properties of the powder laser bed fusion (P-LBF) additively manufactured stainless steel 316L were investigated in the present work. Toward that, micro-pillars were fabricated on different planes of the stainless steel 316L specimen with respect to build direction, and an in situ compression was carried out inside the chamber of the scanning electron microscope (SEM). The results were compared against the compositionally similar stainless steel 316L, which was fabricated by a conventional method, that is, casting. The post-deformed micro-pillars on the both materials were examined by electron microscopy. The P-LBF processed steel exhibits equiaxed as well as elongated grains of different orientation with the characteristics of the melt-pool type arrangements. In contrast, the cast alloy shows typical circular-type grains in the presence of micro-twins. The yield stress and ultimate compressive stress of P-LBF fabricated steel were about 431.02 ± 15.51 − 474.44 ± 23.49 MPa and 547.78 ± 29.58 − 682.59 ± 21.59 MPa, respectively. Whereas for the cast alloy, it was about 322.38 ± 19.78 MPa and 477.11 ± 25.31 MPa, respectively. Thus, the outcome of this study signifies that the AM-processed samples possess higher mechanical properties than conventionally processed alloy of similar composition. Irrespective of the processing method, both specimens exhibit ductile-type deformation, which is typical for metallic alloys. [ABSTRACT FROM AUTHOR]

Hot-dip aluminum alloy is widely used in the engineering fields. However, during the aluminum plating process, Fe inevitably enters and reaches a saturation state, which has a significant impact on the corrosion resistance and microstructure of the coating. Currently, adding Si during the hot-dip aluminum process can effectively improve the quality of the coating and inhibit the Fe-Al reaction. To understand the effect of Si content on the microstructure and electrochemical performance of Al-xSi-3.5Fe coating alloys, the microstructure and post-corrosion morphology of the alloys were analyzed using SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction). Through electrochemical tests and complete immersion corrosion experiments, the corrosion resistance of the coating alloys in 3.5 wt.% NaCl was tested and analyzed. The results show that the Al-3.5Fe coating alloy mainly comprises α-Al, Al3Fe, and Al6Fe. With the increase in Si addition, the iron-rich phase changes from Al3Fe and Al6Fe to Al8Fe2Si. When the Si content reaches 4 wt.%, the iron-rich phase is Al9Fe2Si2, and the excess Si forms the eutectic Si phase with the aluminum matrix. Through SKPFM (Scanning Kelvin Probe Force Microscopy) testing, it was determined that the electrode potentials of the alloy phases Al3Fe, Al6Fe, Al8Fe2Si, Al9Fe2Si2, and eutectic Si phase were higher than that of α-Al, acting as cathode phases to the micro-galvanic cell with the aluminum matrix, and the corrosion form of alloys was mainly galvanic corrosion. With the addition of silicon, the electrode potential of the alloy increased first and then decreased, and the corrosion resistance results were synchronous with it. When the Si content is 10 wt.%, the alloy has the lowest electrode potential and the highest electrochemical activity. [ABSTRACT FROM AUTHOR]

The low strength caused by the single FCC structure of the CrMnFeCoNi high entropy alloy (HEA) limits its application in the field of coating. Here, we prepared high-entropy alloy coatings of CrMnFeCoNi with different ZrC contents on Q235 steel by a plasma transferred arc process. The effects of ZrC on the microstructure and properties of the CrMnFeCoNi HEA coating were investigated by optical microscopy, scanning electron microscope, and X-ray diffraction and by employing a potensiostat/galvanostat. The results showed that ZrC mainly existed in the coatings as a second phase, having little influence on the main crystal structure and micromorphology of the CrMnFeCoNi HEA coating. The hardness of the CrMnFeCoNi HEA coating increased with the ZrC content. ZrC can effectively improve the corrosion resistance of the CrMnFeCoNi HEA coating. In a 1 mol/L NaCl solution with 4 wt% ZrC, the annual corrosion rate was only 5.997% of that of the HEA coating. Nevertheless, the improvement in the wear resistance of CrMnFeCoNi high-entropy alloy coatings was not apparent with the addition of ZrC. Consequently, the addition of ZrC to the FeCoCrNiMn high-entropy alloy coating holds promise for applications in corrosion resistance, particularly in oceanic environments. [ABSTRACT FROM AUTHOR]

The effect of solo and combined addition of Al (3wt. %) and Zn (1wt. %) into gravity-cast Mg-10 wt. % Sn binary alloy on the dry sliding wear test has been investigated using pin-on-disk configuration with varying rotational speed (100 and 200 rpm) under a range of test loads (10, 20, 30, and 40 N). Microstructural characterization and phase analysis of the as-cast Mg-Sn alloys using scanning electron microscope and x-ray diffraction, respectively, have revealed the refinement of the binary alloy microstructure in terms of smaller dendritic arm spacing, uniform and discrete distribution of eutectic phase mixture at the interdendritic locations owing to the alloying additions. Moreover, a significant improvement in microhardness is achieved with increase in amount (wt.%) of alloying elements, depicting the highest hardness in the Mg-10Sn-3Al-1Zn (wt.%) alloy. Simultaneously, the alloying addition even in micro-concentration has been found to reduce the specific wear rate than that of the binary alloy over the entire loading range. The post-wear topographical surface features and chemical analysis using scanning electron microscope and energy-dispersive x-ray spectroscopy of the investigated alloys have suggested the oxidation and abrasion as dominant wear mechanisms. The reduced wear rates in the Al containing alloys are ascribed to the protective and continuous mechanically mixed oxide scale formation during test, which acts as a lubricating layer between the pin and the rotating disk. The discrete oxide island formation at the Zn-lean regions of Zn containing alloys is responsible for their accelerated wear rates. [ABSTRACT FROM AUTHOR]

The aim of this research is to assess the influence of Sn inclusion on the microstructure evolution and age-hardening response of a Zn-4Cu alloy. This is the first study to correlate the age-hardening response to the microstructure of Zn-4Cu alloy reinforced with different Sn contents. A series of Zn-4Cu-Sn alloys were successfully fabricated with different Sn concentrations in the range of 0.0–4.0 wt.% using permanent mold casting. The microstructure of Zn-4Cu-Sn alloys was investigated by means of a scanning electron microscope (SEM) attached with an energy dispersive spectroscope (EDS) and X-ray diffraction (XRD) line profile analysis. At room temperature, the Vickers microhardness measurements were used to assess the age-hardening response of alloys. The results show that the microhardness of the Zn-4Cu (ZC) binary alloy increases a little bit from 76 to 80 HV as the aging time increases from 2 to 128 h, respectively. For aging times up to 16 h, the microhardness of all Sn-containing alloys decreases but then increases again. The lowest hardness belongs to the ZC-1.5Sn alloy, and the Sn-Zn-3.0Sn alloy has the highest; the other alloys fall somewhere in between. At high aging times (64 and 128 h), the microhardness of all Sn-containing samples increased continuously with an increasing Sn content from 0.0 to 3.0 wt.%. When the Sn-containing alloys (3.5 and 4.0 wt.% Sn) were aged for 64 and 128 h, the hardness declined by 7.94% and 8.90% compared to their peak aging hardness values, respectively. By considering the structural changes that occur in the Zn-4Cu-Sn alloys, the reasons for the observed variations in microhardness data with increasing Sn content and aging time were elucidated. X-ray diffraction (XRD) data was analyzed to determine the zinc matrix's lattice parameters, c/a ratio, and unit cell volume variations. [ABSTRACT FROM AUTHOR]

The present study explores the preparation of Al–10wt.%Zn alloy by the casting process. Nano CuO was prepared by the Co-precipitation method. The effect of adding nanostructure of (1wt.% CuO) to Al–10Zn alloy was studied the corrosion effects as-cast and with different aging temperatures (423, 443, and 463 K) for 2 h in 3.5% NaCl aqueous solution after homogenized for 2 h at 500 K at room temperature. Electrochemical measurements (OCP, Tafel, and EIS) were performed to determine the corrosion rate (C.R.) and corrosion current density (Icorr.) to find out corrosion behavior. In addition, microstructures of Al–10Zn and Al–10Zn–1CuO were observed using a scanning electron microscope, EDX mapping, and the optical microscope to investigate the effect of the nanoparticle's addition before and after aging and the corrosion test. The average crystal size and the dislocation density were calculated from the XRD pattern. The results show that the appropriate addition of CuO nanoparticles can refine the Al–10Zn alloy and shift the Al–10Zn alloy to a more noble direction. [ABSTRACT FROM AUTHOR]

In the aircraft industry, the high-strength aluminum alloys AA7075 and AA2024 are extensively used for the manufacture of structural parts like stringers and skins, respectively. Additive manufacturing (AM) of the AA7075-T6 aluminum alloy via friction stir deposition to build continuously multilayered parts on a substrate of AA2024-T4 aluminum has not been attempted so far. Accordingly, the present work aimed to explore the applicability of building multilayers of AA7075-T6 alloy on a substrate sheet of AA2024-T4 alloy via the additive friction stir deposition (AFSD) technique and to optimize the deposition process parameters. The experiments were conducted over a wide range of feed rates (1–5 mm/min) and rotation speeds (200–1000 rpm). The axial deposition force and the thermal cycle were recorded. The heat input to achieve the AFSD was calculated. The AA7075 AFSD products were evaluated visually on the macroscale. The microstructures were also investigated utilizing an optical microscope and scanning electron microscope (SEM) equipped with an advanced EDS technique. As well as the presence phases, the mechanical performance of the deposited materials in terms of hardness and compressive strength was also examined. The results showed that the efficiency of the deposition process was closely related to the amount of heat generated, which was governed by the feeding rate, the rotational speed, and the downward force. AA7075 defect-free continuously multilayered parts were produced without any discontinuity defects at the interface with the substrate at deposition conditions of 1, 2, 3, and 4 mm/min and a constant 400 rpm consumable rod rotation speed (CRRS). The additively deposited AA7075-T6 layers exhibited a refined grain structure and uniformly distributed fragment precipitates compared to the base material (BM). The gain size decreased from 25 µm ± 4 for the AA7075-T6 BM to 1.75 µm ± 0.41 and 3.75 µm ± 0.78 for the AFSD materials fabricated at 1 and 4 mm/min deposition feeding rates, respectively, at 400 rpm/min. Among the feeding rates used, the 3 mm/min and 400 rpm rod rotation speed produced an AA7075 deposited part possessing the highest average hardness of 165 HV ± 5 and a compressive strength of 1320 MPa. [ABSTRACT FROM AUTHOR]

Mg77+xNi20−xLa3 (x = 0, 5, 10, 15) alloys were successfully prepared by the vacuum induction melting method. The structural characterizations of the alloys were performed by using X-ray diffraction and scanning electron microscope. The effects of nickel content on the microstructure and hydrogen storage kinetic of the as-cast alloys were investigated. The results showed that the alloys are composed of a primary phase of Mg2Ni, lamella eutectic composites of Mg + Mg2Ni, and some amount of LaMg12 and La2Mg17. Nickel addition significantly improved the hydrogen-absorption kinetic performance of the alloy. At 683 K, Mg77Ni20La3 alloy and Mg82Ni15La3 alloy underwent hydrogen absorption and desorption reactions for 2 h, respectively, and their hydrogen absorption and desorption capacities were 4.16 wt.% and 4.1 wt.%, and 4.92 wt.% and 4.69 wt.%, respectively. Using the Kissinger equation, it was calculated that the activation energy values of Mg77Ni20La3, Mg82Ni15La3, Mg87Ni10La3 and Mg92Ni5La3 alloys were in the range of 68.5~75.2 kJ/mol, much lower than 150~160 kJ/mol of MgH2. [ABSTRACT FROM AUTHOR]

In this paper, Fe-Cr-C-N-Al-Y wear-resistant surfacing alloy was prepared by open-arc surfacing with self-shielded flux-cored wire. The wear properties of the surfacing alloy were analyzed using an MLS-23 rubber wheel wet sand wear tester. The phase composition and microstructure of the surfacing alloy were analyzed using X-ray diffraction, scanning electron microscope, electron backscatter diffraction and transmission electron microscope; the strengthening mechanism and wear mechanism of the alloy were discussed. The results show that the microstructure of Fe-Cr-C-N-Al-Y surfacing alloy is composed of M + γ-Fe + M7C3 + AlN. When the content of nano-Y2O3 is 0.456 wt.%, the formability of the surfacing alloy is the best, and the wetting angle is the smallest, which is 50.8°; AlN and M7C3 precipitate the most, and the microstructure grain is the smallest. At this time, the hardness value of the surfacing alloy is up to 62.3 HRC, which is 11.8% higher than that of the unmodified surfacing alloy. The minimum wear weight loss is 0.125 g, and the wear resistance is increased by 41.86%. The wear mechanism of the surfacing alloy is mainly a plastic deformation mechanism, and the material removal processes are microcutting and furrow wear. This study provides theoretical guidance for refining primary carbides and improving the wear resistance of high chromium cast iron. [ABSTRACT FROM AUTHOR]

In this study, the effects of magnesium addition on the microstructure and comprehensive properties of Al-5Si-5.3Cu-0.3Sr-0.2Zr-0.2Y-0.06Ti alloys were investigated by optical microscope, scanning electron microscope, transmission electron microscope, hardness tester, and tensile testing machine. It is found that the addition of magnesium increases the number of undissolved particles in the alloy. However, on the one hand, magnesium addition refines the θ′ phase and increases its number density in the alloy. On the other hand, it generates a smaller Q′ phase. Both phases can enhance the precipitation strengthening and dislocation strengthening of the alloy. In addition, adding magnesium reduces the width of the precipitation-free zone (PFZ) and changes the distribution of grain boundary precipitates (GBPs). At 1% magnesium addition, the dislocation strengthening and precipitation strengthening effects of the θ′ and Q′ phases were the best, the width of PFZ was the smallest, and the GBPs were discontinuously arranged along the PFZ. Therefore, a high-strength, high-hardness, and intergranular corrosion-resistant cast aluminum alloy with dense structure, a tensile strength of 364.4 MPa, elongation of 4.87%, hardness of 145.4 HV, and intergranular corrosion grade of 3 was obtained. [ABSTRACT FROM AUTHOR]

The main aim of this research is to analyze the mechanical performances of the influence of silicon carbide (SiC) particles with AA6351 aluminum alloy. The aluminum metal matrix composites were prepared with liquefying stir casting to produce the metal matrix composites (MMCs). The following weight fractions are AA6351-0% SiC, AA6351-2.5% SiC, AA6351-5% SiC, and AA6351-7.5% SiC utilized to compose the MMCs. The mechanical performances like hardness, flexural, impact, compressive, and tensile studies were investigated on the processed MMCs. The scanning electron microscope (SEM) was employed to examine the strengthened particle of SiC. During the SEM examinations, uniformly dispersed SiC-strengthened particles were analyzed. The entire MMCs specimens achieve greater mechanical characteristics; the specimen fabricated with a maximum volume fraction of 7.5 wt% of SiC accumulates higher strength than the other volume fractions samples. The SiC plays a very tedious role in improving mechanical attributes. The fabricated MMCs were highly utilized in the applications of automotive and aerospace usages. This application is fully employed with lesser weight and maximum strength conditions to fulfill the mechanical performances. The stir-casting process was a highly efficient technique to compose better MMCs to achieve greater strength. [ABSTRACT FROM AUTHOR]

The effect of graphene nanosheets (GNPs) on the microstructure and corrosion resistance of ADC12 alloy in HCl solution were researched by optical microscope, scanning electron microscope, energy-dispersive spectrometer, x-ray diffraction and electrochemical measurements. The microstructural evolution revealed that the addition of GNPs could significantly refine the α-Al, Si and β-Al5FeSi phases, thus optimizing the microstructure of ADC12 alloy. The results of electrochemical experiments demonstrated that the corrosion current density of ADC12-0.9 wt.% GNPs alloy (1.18 mA cm−2) was 62.7% lower than that of the matrix (3.17 mA cm−2), and the corrosion potential (− 534 mV) was 8.4% higher than that of ADC12 (− 579 mV). Moreover, the value of polarization resistance (70.74 Ω cm2) was highest when adding 0.9 wt.% GNPs, indicating the improved corrosion resistance. The results of immersion tests indicated that the corrosion rate of the ADC12-0.9 wt.% GNPs alloy (VM = 16.31 ± 0.81 mg cm−2 d−1) was 62.3% lower than that of the matrix (VM = 43.16 ± 1.69 mg cm−2 d−1). Moreover, the effect of GNPs on the micro-galvanic corrosion for ADC12 alloy was discussed. [ABSTRACT FROM AUTHOR]

In this study, CNTs-reinforced Al-Cu-Mg-Si nanocomposites were successfully fabricated by high-energy ball milling (HEBM) combined with semi-solid stir casting. Then, the composites were subjected to hot extrusion. The Microstructure and Phase analysis of the CNT/Al-Cu-Mg-Si composites were characterized by an Optical microscope, Scanning Electron Microscope (SEM), and XRD. Additionally, density, hardness, and wear were measured. The results revealed that the addition of CNTs effectively inhibited the growth of α-Al grains, and the grains were dramatically refined. Additionally, the dynamic recrystallization degree of the composite extruded rod gradually increased from 1.3% to 68.4%, with the content of CNTs from 0 wt% to 3.0 wt%. The hardness values of the composite increased with an increase in CNTs. Moreover, the friction factor and wear rate of the composites first decreased and then increased as the content of CNTs increased. When 1.5CNTs were added, the friction coefficient (COF) and wear rate of composites reached the minimum of 0.3577 and 3.42 mg/km, which were reduced by 30.09% and 73.03% compared with Al-Cu-Mg-Si alloy, respectively. [ABSTRACT FROM AUTHOR]

Wear behavior of titanium alloys of Ti-4.5wt%Al + xFe (x: 2,4,6,8) produced by spark plasma sintering was investigated in order to highlight the effects of the iron additive on wear rate and coefficient of friction (COF). These research objectives were accomplished by a dry sliding experimental technique using the Tribometer (version 8.1.8) Anton Paar machine, which was carried out under normal loads at 10 N and 20 N with a linear speed of 0.06 cm/s. Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques were used to characterize the titanium alloy specimens. The results indicated that the wear rate increases with an increase in the applied normal load. A minimal coefficient of friction of 0.047 and a wear rate of 1.033 × 10−5 (mm3/N/M) were observed for Ti-4.5 wt% Al + 4 wt% Fe with respect to sliding at 10 N. While at a normal load of 20 N, a minimal friction coefficient of 0.015 and a wear rate of 1.74 × 10−5 (mm3/N/M) were obtained for Ti-4.5 wt% Al + 4 wt% Fe. [ABSTRACT FROM AUTHOR]

High entropy alloys (HEA) are one of the modern-era alloys accelerating with greater velocity because of their excellent properties and different applications. In the present paper, we have successfully fabricated HEA (23Fe-21Cr-18Ni-20Ti-18Mn) powders by ball milling the elemental Fe, Cr, Ni, Ti, and Mn powders for 15 h. The advancement of the milling process and phase transformation of HEAs were studied by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The crystallite size and the lattice strain of the HEA were calculated by using the Williamson-Hall (W-H) equation and the values were found to be 7 nm and 0.0176%, respectively. Similarly, the true lattice parameter was calculated using the Nelson–Riley (N-R) extrapolation method, and the value was found to be 3.544 Å. We have successfully investigated the electrochemical response of 15 h ball milled 23Fe-21Cr-18Ni-20Ti-18Mn HEA powders to determine the ascorbic acid (AA) using cyclic voltammetry. We have modified the carbon paste electrode with ball milled HEA of concentrations 0, 2, 4, 6, 8, and 10 mg, and among them, 8 mg HEA modified carbon paste electrode (HEA-MCPE) depicted the highest current sensitivity. We reported the effect of modifier concentration, analyte concentration, scan rate, and pH on the oxidation peak of AA. The electrochemical active surface area of carbon paste and MCPE was calculated using the Nernst equation and the values were found to be 0.0014 cm2 and 0.0027 cm2, respectively. The fabricated HEA-MCPE showed excellent current sensitivity, stability, anti-fouling, and selectivity. [ABSTRACT FROM AUTHOR]

A recently developed solid-state joining technique called "friction stir spot welding" (FSSW) is used to combine metal alloys with low weldability. Significant experimental work for this study is concentrated on the FSSW of AA6063 and AA5083. The study involved fixture setup and welding pattern parameters for the sizes of the material, all of which were done on a milling machine. A cylindrical shoulder with a concave (10°) square pin profile was taken into consideration using various process parameters. The tool material is heat-treated high-carbon steel. The Taguchi L9 orthogonal array is employed for the experimental model. The influence of FSSW factors including spindle speed, time, and depth was studied, along with the relationship between tensile strength, hardness at the contact region, and hook development, which would be a nominal metallurgical pledge established in the welding zone among the interacting sheet plate. The hook structure was found in the area of contact, and thermomechanical effects were seen in the spot-welding area. It has been determined that the influencing variables are spindle speed and plunge depth. As a consequence, it was determined that a tool spindle speed of 1200 rpm, a time of 25 seconds, and a plunge depth of 0.10 mm offer better mechanical properties. The microstructural analysis of welded region was carried out using a scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

Ti–Si–Fe alloys extracted from high-titanium blast furnace slag were utilized to replace part of the silicon powders, and then nitride/oxynitride bonded SiC ceramics were prepared by reactive sintering in graphite bed. Ti–Si–Fe alloys could react with CO/N 2 at a low temperature (1200 °C), and the addition of Ti–Si–Fe alloys could reduce the nitriding temperature of Si. Density functional theory calculations suggested that Ti–Si–Fe alloys enhanced reaction activity via weakening the strength of C O and N N bonds. The regional equilibrium phase diagrams of Si–C–N–O and Ti–Si–C–N–O under CO/N 2 atmosphere were calculated by thermodynamics. The change of whiskers morphology was observed by scanning electron microscope. Furthermore, the bulk density, the cold modulus of rupture, and the cold compressive strength improved with Ti–Si–Fe alloys content. The results showed that the addition of Ti–Si–Fe alloys not only significantly promoted nitriding of Si and formation of Si 3 N 4 whiskers, but also improved the mechanical properties of the samples. [ABSTRACT FROM AUTHOR]

The effects of La and Y on the microstructure and mechanical properties of cast Al-Si-Cu alloys were investigated by X-ray diffractometer (XRD), optical microscope (OM), and scanning electron microscope (SEM). The results indicated that the addition of La and Y had a great effect on the refinement of α-Al grains, the modification of eutectic Si phase, and the reduction of β-Al5FeSi length in Al-Si-Cu alloys. The A380 + 0.6 wt.% La/Y alloy exhibited the best microstructure and mechanical properties. The UTS and EI of the A380 + 0.6 wt.% La/Y alloy were 215.3 MPa and 5.1%, which were 22.9% and 37.8% higher than those of the matrix alloy, respectively. In addition, neither Al11La3 nor Al3Y generated by the addition of La and Y could not serve as the nucleation core of α-Al grains, so the grain refinement of α-Al originated from the growth limitation and constitutional supercooling. Since La and Y promote twinning generation and constitutional supercooling, the eutectic Si phase also changed from stripe-like to short fibrous or even granular and was significantly refined. Furthermore, thermodynamic calculations indicated that the Al11La3 phase was formed first and the Al3Y phase was generated on the Al11La3 phase. [ABSTRACT FROM AUTHOR]

High-cycle fatigue (HCF) is a critical property of metastable β Ti alloys in aerospace applications. In this work, the HCF behavior and corresponding microscale deformation mechanisms of a metastable Ti-5Al-5Mo-5V-1Cr-1Fe (Ti55511) alloy with a basket-weave structure were investigated. HCF and its deformation mechanisms of a Ti55511 alloy were systematically studied in the deformed condition by using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and electron backscatter diffraction (EBSD). It was found that the Ti55511 alloy exhibited an excellent HCF strength (107 cycles, Kt = 1, R = 0.06) of 738 MPa. The fractographic investigation demonstrated that fatigue striations and secondary cracks were the main features in the crack initiation zone. Dislocation analyses indicated that the HCF deformation of the basket-weave microstructure was mainly affected by the dislocation slipping of the primary α (αp) phase. In addition, the dislocation pile-up at the αp/βtrans interface led to crack initiation. EBSD analyses indicated that the prismatic type slip system of the αp phase was preferentially activated during the HCF deformation process of the Ti55511 alloy, followed by the basal type and pyramid type systems. [ABSTRACT FROM AUTHOR]

In recent years, Mg alloys have attracted increased attention for biomedical application owing to their good biodegradability, biocompatibility, and biomechanical properties. However, rapid corrosion is still one of the most common limitations for their implanted application. In this work, the microstructure and corrosion behavior of the solution- and aging-treated Mg-xGd-1Zn-0.4Zr (x = 3, 6, and 9 wt%, denoted as GZ31K, GZ61K, and GZ91K, respectively) alloys were studied using optical microscope (OM), scanning electron microscope (SEM), immersion tests, electrochemical tests, and quasi in situ corrosion method. The results show that block Gd-rich precipitates and needle-like Zr-Zn-rich precipitates are formed as well as α-Mg matrix. With the increase in Gd content, the precipitates increase and the grain size first reduces and then increases. Corrosion experiment results show that the GZ61K alloy has the best corrosion resistance and the GZ91K alloy shows the highest corrosion rate among the three alloys in simulated body fluid (SBF). It is found that α-Mg is preferentially corroded and the precipitates have better corrosion resistance as compared to the α-Mg matrix. The GZ61K alloy with the corrosion rate of 0.23 mm/y in SBF shows a promising prospect for biomedical application. [ABSTRACT FROM AUTHOR]

In the present work, the effect of thermal cycles on the physical and thermal properties of AZ31 alloy and AZ31/5wt%SiC and AZ31/10wt%SiC composites was investigated. Samples were prepared using the stir casting method and then subjected to precipitation hardening. Thermal cycles were done for as-cast and aged samples with V-shaped notch under 300, 600, and 900 heating and cooling cycles at 150 and 350 °C. The crack length (CL) was evaluated using optical microscope (OM), scanning electron microscope (SEM), and energy-dispersive scanning electron (EDS) analysis. Also, density, porosity, thermal expansion coefficient of the samples were evaluated. X-ray diffraction (XRD) analysis was employed to assess the phases present in the material. The results demonstrated that by increasing the number of thermal cycles up to 600 at 150 °C and 350 °C, the porosity and density of the as-cast and aged AZ31 alloy decreased and increased, respectively; however, the density and open porosity were remained constant for the composite samples. The crack's length enlarged with increasing the thermal cycles from 300 to 600 µm at 150 °C and 300 to 900 µm at 350 °C. It was found that the reinforcement and precipitates prevented the rapid growth of the crack in the magnesium matrix. All in All, composite and the aged samples demonstrated better thermal fatigue resistance compared with that of the unreinforced alloy and as-cast samples, respectively. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of Si content on the microstructures and properties of directionally solidified (DS) Fe-B alloy, a scanning electron microscope (SEM) with an energy dispersive spectrum (EDS), and X-ray diffraction have been employed to investigate the as-cast microstructures of DS Fe-B alloy. The results show that Si can strongly refine the columnar microstructures of the DS Fe-B alloy, and the columnar grain thickness of the oriented Fe2B is reduced with the increase of Si addition. In addition, Si is mainly distributed in the ferrite matrix, almost does not dissolve in boride, and seems to segregate in the center of the columnar ferrite to cause a strong solid solution strengthening and refinement effect on the matrix, thus raising the microhardness of the matrix and bulk hardness of the DS Fe-B alloy. [ABSTRACT FROM AUTHOR]

This study investigated the microstructure, hardness, tensile and tribological behaviour of a cooling slope Al--Si--Mg alloy following ECAP and T6 heat treatment. The optical and scanning electron microscopes were applied to investigate the microstructure of the as-cast material and heattreated ECAPed Al--Si--Mg alloy. The dry sliding wear test was tested with three different loads of 10 N, 50 N, and 100 N with constant sliding speed and sliding distance at 1.0 m/s and 9000 m, respectively, using the pin-on-disc tribometer. The hardness and tensile properties were evaluated through microhardness, UTS, and YS measurement for the as-cast Al--Si--Mg alloy, both heat-treated with and without ECAPed alloys. Moreover, wear rate and COF in the Al--Si--Mg alloy with different loads were analysed and linked with microstructural and strength behaviour after the ECAP process. Meanwhile, these analyses of results were correlated with the behaviour of the as-cast Al--Si--Mg aluminium alloy and heat-treated non-ECAPed alloy. Results demonstrated that a combination of ECAP processing and T6 heat treatment improves the mechanical behaviour, while the COF and wear rate are improved at a load of 100 N. [ABSTRACT FROM AUTHOR]

FeCrMnNi high-entropy alloys prepared by vacuum induction melting were tested and characterized using an X-ray diffractometer, a scanning electron microscope, a micro hardness tester and a universal tensile tester to investigate the effects of the heat treatment temperature on the microstructure and mechanical properties of the alloys and the heat-resistant corrosion properties of FeCrMnNi alloy after annealing at 800 °C. It is a high-entropy alloy with a typical dendritic (DR) morphology. With the increase in the heat-treatment temperature, the amount of ultrafine precipitates with the BCC structure in the matrix increased; furthermore, the amount of ultrafine precipitates started to decrease at temperatures above 900 °C, and the DR structure gradually weakened. After heat treatment at temperatures above 800 °C, the alloy showed a tensile strength of 721.1 MPa and an elongation at break of 26.7%, which indicates improved strength of the alloy while maintaining good plasticity, mainly because a large amount of nanoscale particles precipitated between the DR structures and enabled fine grain strengthening. Therefore, an appropriate heat-treatment temperature helps to improve the overall mechanical properties of the high-entropy alloy. [ABSTRACT FROM AUTHOR]

A novel aluminum matrix composites (AMCs) reinforced by multiphase intermetallic compounds were fabricated through a conventional casting approach. The microstructure, compression properties and tribological behavior of the AMCs were detailed studied by the scanning electron microscope (SEM), x-ray diffraction (XRD), and electron probe microanalysis (EPMA). The results demonstrated that the fraction of precipitated multiphase intermetallic compounds gradually increased with the increase of high-entropy alloy (HEA) adding content, and the grain size of α-Al obviously was reduced. The irregular multiphase intermetallic compounds, such as Al70Cr20Ni10 and AlTiCrSi, are distributed in the Al matrix. However, the Al2Cu and Al7Cu4Ni distributed in inter-dendrites of α-Al. In addition, the compression strength of AMCs reinforced by 20.0 wt.% HEA addition was significantly enhanced to 530 MPa due to the precipitation of multiphase intermetallic compounds. Meanwhile, its compression strain was higher than 25%. Compared with pure Al, the microhardness of AMCs was extremely increased to 160 HV when the addition content of HEA was up to 20.0 wt.%. When the addition amount of HEA reached 10.0 wt.%, the COF of the ACMs was decreased by 51.6% from 0.766 to 0.371. When the HEA content was up to 20.0 wt.%, the wear rate reached the minimum of 4.87 × 10−5 mm3/N·m, which was reduced by 31.9% compared with pure Al. Furthermore, the strengthening effect and wear mechanism of AMCs reinforced by HEA addition was also discussed. [ABSTRACT FROM AUTHOR]

A complex concentrated noble alloy (CCNA) of equiatomic composition (Ag20Pd20Pt20Cu20Ni20–20 at. %) was studied as a potential high—performance material. The equiatomic composition was used so that this alloy could be classified in the subgroup of high—entropy alloys (HEA). The alloy was prepared by induction melting at atmospheric pressure, using high purity elements. The degree of metastability of the cast state was estimated on the basis of changes in the microstructure during annealing at high temperatures in a protective atmosphere of argon. Characterisation of the metallographically prepared samples was performed using a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), differential scanning calorimetry (DSC), and X–ray diffraction (XRD). Observation shows that the microstructure of the CCNA is in a very metastable state and multiphase, consisting of a continuous base of dendritic solidification—a matrix with an interdendritic region without other microstructural components and complex spheres. A model of the probable flow of metastable solidification of the studied alloy was proposed, based on the separation of L—melts into L1 (rich in Ni) and L2 (rich in Ag). The phenomenon of liquid phase separation in the considered CCNA is based on the monotectic reaction in the Ag−Ni system. [ABSTRACT FROM AUTHOR]

Device-related infection or inflammatory and stress shield are still the main problems faced by titanium alloy implants for long-term implantation application; therefore, it is of great significance to design an alloy with low elastic modulus and good antibacterial properties as well as good biocompatibility. In this paper, Ti-13Nb-13Zr-xCu(x = 3, 7 wt.%) alloys were designed and prepared to reveal the influence of Cu content on the elastic modulus and antibacterial property. X-ray diffractometer, metallographic microscope, scanning electron microscope, and transmission electron microscope were used to study the phase transformation, microstructure, mechanical properties, antibacterial properties, and cytotoxicity of the alloys. The experimental results have demonstrated that the antibacterial performance and the elastic modulus were significantly improved but the corrosion resistance deteriorated with the increase of the copper content. Ti-13Nb-13Zr-3Cu with a low modulus of 73 GPa and an antibacterial rate of over 90% against Staphylococcus aureus (S. aureus) exhibited great potential as a candidate for implant titanium in the future. [ABSTRACT FROM AUTHOR]

Aluminium alloys have low density and good mechanical properties, making them suitable for the manufacture of mechanical structures where low weight is critical. However, when these alloys are subjected to elevated temperatures, their mechanical properties deteriorate significantly. The aim of this study is to investigate the effect of temperature on the mechanical properties of aluminium alloy, EN AC-Al Si12CuNiMg. For this purpose, an experimental investigation was performed at ambient and elevated temperatures on aluminium alloy samples prepared by casting. Tensile and hardness tests were carried out to characterize the mechanical properties of this material. Additionally, an optical microscope was used to examine the microstructures of this alloy. Finally, a scanning electron microscope was used to analyze the fracture modes of this material. The results show that the mechanical properties such as tensile strength, yield strength, and Young's modulus of this alloy dramatically decrease when the temperature exceeds 250oC. The microstructural investigation reveals several factors that are detrimental to the mechanical properties of this alloy. This includes coarse-grained structures, micro-pores, and several intermetallic compounds. Furthermore, fractography reveals a minor cleavage-like pattern and micro-cracks on the fracture surface of all failed samples under various temperatures, indicating semi-brittle fracture mode. [ABSTRACT FROM AUTHOR]

The effects of Ag content and hot-rolling on the microstructure and mechanical properties of Zn-1.5Cu-xAg-0.1Zr(x = 0, 0.1, 0.5, 1.0) alloys were investigated. The microstructure, phase composition and fracture morphology of the alloys were observed and analyzed by optical microscope, x-ray diffraction, scanning electron microscope, energy dispersive spectrometer and universal mechanical testing machine. The results show that Ag has the effect of grain refinement. After alloying, the grain size of as-cast Zn-1.5Cu-xAg-0.1Zr alloy decreased first and then increased, and the minimum grain size of as-cast Zn-1.5Cu-0.5Ag-0.1Zr alloy was refined to 64.18 μm. At the same time, new phase AgZn3 began to precipitate, the yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of alloys were also up to 97.35 MPa, 139.25 MPa and 7.60%, respectively. After hot-rolling, the grain of Zn-1.5Cu-xAg-0.1Zr alloy was broken and new phase CuZn5 was precipitated. The mechanical properties were significantly improved, and the maximum YS, UTS and EL of as-rolled Zn-1.5Cu-1.0Ag-0.1Zr alloy were 218.14MPa, 244.83MPa, 64.50%, respectively. [ABSTRACT FROM AUTHOR]

Recent investigations have highlighted the multi-resolution and high throughput characteristics of the spherical indentation experimental and analysis protocols. In the present work, we further demonstrate the capabilities of these protocols for reliably extracting indentation stress-strain (ISS) responses from the microscale constituents as well as the bulk scale of dual phase materials exhibiting bimodal microstructures. Specifically, we focus on bimodal microstructures produced in an α–β Ti6242 sample. Combining the multi-resolution indentation responses with microstructural statistics gathered from the segmentation of back-scattered electron images from the scanning electron microscope allowed for a critical experimental evaluation of the commonly utilized Rule of Mixtures based composite model for the elastic stiffness and plastic yield strength of the sample. The indentation and image analyses protocols described in this paper offer novel research avenues for the systematic development and critical experimental validation of composite material models. [ABSTRACT FROM AUTHOR]

The development of magnesium alloys with superior plasticity and favorable strength is still challenging in aerospace industry. Herein, hot extruded Mg-xNd-2.0Sm-0.4Zn-0.4Zr alloys (x = 0, 0.5, 1.0, 1.5, 2.0 and 2.5 wt.%) were rationally designed and easily prepared in order to implement the favorable combination of strength and plasticity. The effects of Nd element addition on the microstructure and mechanical properties of the hot extruded alloys were systematically investigated by optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The OM results indicated that the grain size of the hot extruded alloys decreased from 27.1 to 14.1 μm with increasing Nd addition from 0 to 2.5 wt.%. Some coarse β phases existed at the grain boundary when the addition of Nd element increased to 2.0 wt.%. The TEM results showed that the nanoscaled basal lamellar precipitates, granular precipitates and prismatic lamellar precipitates formed in α-Mg matrix. And the amount of precipitated phase increased obviously with the increase of Nd element addition. The ultimate tensile strength increased significantly from 203 ± 3.0 to 237 ± 2.5 MPa, and the elongation decreased from 30.5 to 21.2 % when the Nd elements increased from 0 to 2.5 wt.%. The fractographs of the hot extruded alloys could be classified as ductile fracture. [ABSTRACT FROM AUTHOR]

Main aim of this study is to examine change of microstructural and the mechanical properties of Al-7075 alloy depending on B content added with different proportions. Rapid solidification process used to produce the alloys was carried out with a single roll melt spinner via a wheel with a rotational speed of 25 m/s. For the microstructural characterization of the alloys, a scanning electron microscope and X-ray diffraction analyzes were used. According to obtained results, it can be said that B addition led to modification of dimensions and shapes of both α−Al and intermetallic phases occurred, it reduced average grain size from 0.45 μm to 0.34 μm in the microstructure. The B addition also led to dramatically increase in microhardness of the Al-7075 alloy. The microhardness of the alloy with 0.4 wt. % B is 0.19 GPa, this is clearly one times higher than that of the alloy without B addition. The microhardness of the alloy with 1 wt. % B is 0.21 GPa, this is also slightly higher than that of the alloy with 0.4 wt. % B. [ABSTRACT FROM AUTHOR]

The microstructure and properties of the aged Cu-Cr-Zr-Nb alloy were studied by means of hardness tester, universal tensile testing machine, conductivity meter, X-ray diffraction, scanning electron microscope, and transmission electron microscope. The results indicated that the hardness and TS (tensile strength) of the Cu-Cr-Zr-Nb alloy increased first and subsequently decreased with increasing the aging temperature. Nevertheless, the electrical conductivity is gradually increasing. The aged Cu-Cr-Zr-Nb alloy was mostly made up of Cu matrix, Cr particles, Cr 2 Nb, and CuZr compounds. Due to the effects of dislocations accumulated by cold drawing and twins produced during the aging process, the softening temperature of the alloy reached 590 ℃. When the Cu-Cr-Zr-Nb alloy was aged at 490 ℃, < 111 > replaced < 110 > in the optimal orientation of the alloy, and the KAM (kernel average misorientation) value inside the alloy was the largest. The alloy exhibited great comprehensive properties at 490 ℃ for 1 h, with a hardness of 144.4 HBW, a TS of 521 MPa, and an electrical conductivity of 78.3%IACS. The contribution value of YS (yield strength) at different aging temperatures was further calculated. The computational results showed that precipitation strengthening was the main strengthening mechanism of the Cu-Cr-Zr-Nb alloy, and fine-grained strengthening and dislocation strengthening simultaneously played a supplementary role. • Due to the effects of dislocations accumulated by cold drawing, precipitation strengthening of Cr and twins produced during the aging process, the softening temperature of the Cu-Cr-Zr-Nb alloy reaches 590 ℃. • The Cu-Cr-Zr-Nb alloy exhibits great comprehensive properties at 490 ℃ for 1 h, with a hardness of 144.4 HBW, a tensile strength of 521 MPa, and an electrical conductivity of 78.3 %IACS. • The computational results show that precipitation strengthening is the main strengthening mechanism of the Cu-Cr-Zr-Nb alloy. [ABSTRACT FROM AUTHOR]

The corrosion behavior and microstructure of Mg-3Zn-1Mn-xSr (x = 0, 0.5, 1.0, 1.5, 2.0 wt.%) alloys are investigated by optical microscope (OM), scanning electron microscope (SEM), electrochemical tests and immersion experiments equipped with a dynamic corrosion device. The introduction of Sr element changes the distribution of Mg7Zn3 phase in the Mg-3Zn-1Mn alloy, promoting its precipitation at the grain boundary. Decrease in grain size and second phase spacing can be observed with the increase of Sr content, and the size of semi-continuous second phases (Mg7Zn3 + Mg17Sr2) distributed along grain boundary increases. The corrosion resistance of Mg-3Zn-1Mn-xSr alloys increases with the suitable addition of Sr, but decreases with the addition of excessive Sr, indicating that the critical value exists for the addition of Sr to obtain the optimal corrosion resistance. Optimal corrosion performance (CR = 1.213 ± 0.02mm/y, Icorr = 2.80μA/cm2) of Mg-3Zn-1Mn-1Sr alloy is concluded by immersion tests and electrochemical measurements, and its corrosion morphology manifests uniform corrosion pits and dense structure due to mass accumulation of corrosion products on the damaged surface of Mg matrix. The synergistic effect of the grain size and second phase is used to explain the influence of the variation of Sr content on the corrosion performance of Mg-3Zn-1Mn-xSr alloys. [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]

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]

Developments in engineering and medicine have allowed patients' health and quality of life to be supported by implants. Unfortunately, widely used titanium-based alloys with aluminum and vanadium are not ideal materials. The first problem is a mechanical mismatch between human bone and the implant material, and the second issue is the presence of Al or V, which are harmful for the human body and health. This article focuses on the holistic design and production of titanium-based materials with vital elements. The zoned, gradient element can exhibit better mechanical properties and improve the connection between the implant and the bone. The samples in two constructions were built with two different zones. The powders for samples were prepared using the powder metallurgy technique with sieve separation. Phillips X-ray X′Pert diffractometer and PDF4 + database performed the phase composition analysis. The Scanning electron microscope allow the samples observation. Stereological methods assessed porosity and PAR M370 Scanning Electrochemical Workstation. The designed technology based on the powder metallurgy method allows for producing functional, two-zoned graded materials with variable porosity. The phase composition analysis confirmed partially synthesis. Additionally, the observation of the microstructure of the sintered samples revealed the presence of two permanently connected zones. Preliminary mechanical research was conducted to evaluate the potential use of the material as an implant material. The proposal to use two-zone construction of components for implants is dictated by the possibility of personalizing implants for patients, taking into account personal characteristics and needs. [Display omitted] • The functionally graded materials based on vital elements were successfully fabricated using powder metallurgy method. • Highly porous FGM with interconnected porosity was prepared by powder metallurgy. • The porous and microstructure evolution in each gradient layer of FGM is revealed. • The effect of Tin use as Process Control Agent were confirmed and allow to obtain more uniform powders. [ABSTRACT FROM AUTHOR]

In this paper, the hot deformation behavior of A357 alloy was investigated by hot compression tests. Isothermal hot compression simulation tests for A357 alloy were carried out at the conditions of deformation temperature of 350-470 °C, strain rate of 0.001-10 s−1 and engineering strain of 50%. Based on the Prasad instability criterion and dynamic material model, the hot processing maps of A357 alloy were constructed. The microstructure of compressed samples at different areas of the hot processing map was characterized by metallographic and scanning electron microscope and transmission electron microscope. The experimental results showed that the unstable processing zone of A357 alloy was mainly distributed in the high strain rate (10 s−1) and low-temperature (350, 380 °C) region. With an increase in the strain, the unstable zone expanded from low temperature to high temperature (470 °C). The ideal deformation conditions were deformation temperatures of 380-410 °C and strain rates of 0.001-0.01 s−1, and deformation temperatures of 440-470 °C and strain rates of 0.01-1 s−1. When the A357 alloy was extruded with the optimal hot processing parameters, the results suggested that hot extrusion could make the microstructure uniform and fine, thereby improving mechanical properties, especially when the elongation was up to 19.5% higher than the as-cast A357 alloy. [ABSTRACT FROM AUTHOR]

The Cu-Cr-Nb alloys were prepared by vacuum induction melting with different cooling methods. The effects of niobium contents and different cooling methods on the microstructures and properties of these alloys were investigated. The microstructures were characterized by optical microscope, scanning electron microscope and transmission electron microscope. The electrical conductivity, hardness and the tensile strength of Cu-Cr-Nb alloys were tested as well. The results showed that the as-cast microstructures of Cu-Cr-Nb alloys consist of primary α phase dendritic and eutectic phase. With the addition of element Nb, the microstructures were refined and the secondary dendritic arm spacing obviously decreased. Compared with the furnace cooling, the homogeneous and refined microstructures were obtained by the graphite mold, and the hardness of the alloys is enhanced greatly. After the heat treatment, two reinforcing phases of Cr and Cr2Nb are precipitated from the copper matrix. The comprehensive properties were obtained when the Nb content is 0.4%. The Cu-1.2Cr-0.4Nb alloy performed by direct aging treatment without solution treatment exhibits the higher performance, the hardness and electrical conductivity are 143HB and 84%IACS, respectively. In addition, the tensile strength and the elastic limit of the Cu-1.2Cr-0.4Nb alloy can reach up to 413.0 and 238 MPa. [ABSTRACT FROM AUTHOR]

In the present paper, the microstructure evolution of semi-solid metal slurry was investigated. The material was tested by rheocasting route. In order to better estimate the materials behavior, the investigation was performed on three series of samples. The rheocasting was conducted different stirring speed of 500, 1000 and 1500rpm and 0.3 solid fraction, before casting. The microstructure was analysed using an optical and scanning electron microscope. The results show that the relationship between the equivalent diameter of Si and α - Al particles with stirring speed can be well fitted to quadratic or linear equation. The results from this study can also be used to optimize the process and study mechanism of the rheocasting process. [ABSTRACT FROM AUTHOR]

This research examines the effect of wear testing parameters on the wear behavior of AZ91 alloy prepared through rotary-die equal channel angular pressing (RD-ECAP). An AZ91 alloy was processed by RD-ECAP method at 573 K for up to 16 passes to reduce the grain size to ~ 5 µm. The properties of the alloys produced by RD-ECAP were compared with the as-received alloy. In order to measure the wear behavior of RD-ECAP manufactured alloy with the as-received alloy, wear tests were performed using ball-on-disk apparatus with specific loading conditions and varying sliding speeds. Surface analysis was used to show the presence of delamination, wear debris and plowing using scanning electron microscopes (SEM). The findings showed that, due to the grain refinement and homogeneity of the second phase distribution, RD-ECAP processed magnesium alloys possess increased wear resistance compared to the initial condition (unprocessed alloy), which makes them suitable for applications in aerospace, automotive and structural industries. Besides, the weight loss reduced with the increase of RD-ECAP pass numbers. Furthermore, increasing in applied load had a more dramatic effect on wear resistance compared to increasing sliding speed and sliding time. [ABSTRACT FROM AUTHOR]

To study the application of scanning electron microscope in metal materials. The properties of metals and their alloys are determined by chemical composition, crystal structure and microstructure. Scanning electron microscope (SEM) in the research category, from metal fracture study, alloy and related components, powder contact gold, element diffusion and inclusion analysis, contact materials research and so on several aspects, through the relevant data, to concrete analysis of metal materials in the application of scanning electron microscope. The scanning electron microscope (SEM) can correspond the observation of metal structure with the analysis of chemical composition, and is especially helpful for the analysis of metal fracture due to the large focal depth and the three-dimensional sense of electronic image. Scanning electron microscope analysis element range: the spectrometer is B5~Ug2, the spectrometer is Na11~Ug2. The sensitivity of detected elements is about 0.2%~0.01%. Antioxidant coatings of metals and their alloys can be developed. It can determine the diffusion rate, diffusion layer thickness, coating composition and phase composition of the element under different process systems. The diffusion and mechanism of coating, heat diffusion welding, bimetal and explosion composite metal under different process systems can be studied. It is convenient to study the oxidation and corrosion mechanism of metals and alloys and to evaluate the brittleness of materials, determine the fracture of materials in what state, study the change of phase composition and grain boundary composition, determine the degree of segregation of alloy elements, etc. Scanning electron microscope can not only observe the surface morphology of metal material, but also conduct qualitative and quantitative analysis of metal material elements, so that the surface morphology and element analysis correspond to each other, which is conducive to the better use and development of metal materials, and with the development of science and technology, will play a greater role. [ABSTRACT FROM AUTHOR]

In the current research, the effect of Ag on the mechanical properties of Ti5Al2.5Fe alloy was investigated. The Ti5Al2.5Fe alloy, with different amounts of Ag ranged from 1 to 5 wt. % was prepared by mechanical mixing and then fabricated by hot pressing at 950 oC for 15 min under 50 MPa. Three holding steps were applied to the powder compacts to restrain the liquid phases inside graphite die before reaching the maximum sintering temperature. The sintered samples were subjected to hardness, bending and wear tests to study the effect Ag on the mechanical properties of Ti5Al2.5Fe alloy. The microstructural characterization was carried out by means of optical and scanning electron microscope. The results showed that Ag played a differential role on the mechanical properties supported by microstructural constituents. The bending strength and hardness of the produced samples increased with the addition of Ag, the hardness of the alloys then tended to decrease with increasing Ag content but still remained above the hardness of Ti5Al2.5Fe alloy. Wear test also showed similar trends with hardness test results. Finally, the optimum Ag content for the Ti5Al2.5Fe alloy was determined as 1 wt.%. XRD analysis showed that undissolved Ag content was the main reason for the decrease in the mechanical properties. [ABSTRACT FROM AUTHOR]

Cobalt-Nickel (Co-Ni) alloy coatings were prepared by jet electrodeposition on brass substrate under different Co2+/Ni2+ ratio contents (M = 2:1, 1:1, 1:2 and 1:3) and solution flow rates (from 2.0 to 4.5 L/min). The surface morphology, element content, and phase structure of the coating were observed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD). The hardness and wear resistance of the coatings were also measured. The results showed that the Co content in coatings was greater than 70%, no matter at what flow rate and concentration. With an increase of the flow rate, the Co content in the coating increases, and the grain size on the surface of the coating decreases, which leads to increased hardness of the coating. However, the flow rate of the plating solution has little effect on the grain growth orientation, and the phase structure is dominated by the elemental content of the coating. The coatings are in a single phase of hexagonal close-packed (HCP) when the Co content is more than 80%, while the coatings are in dual phases of the HCP and face-centered cubic (FCC) when the Co content is less than 80%. With an increase in the Co content, the grain size decreases, and consequently, the hardness and wear resistance of the alloy increase. A Co-Ni alloy coating with stable composition can be obtained when the ratio of Co2+ to Ni2+ is 2:1. [ABSTRACT FROM AUTHOR]