Microstructure Of Alloy Research Articles

Effect of pinless friction stir processing on microstructure and properties of surface modification layer of 2024 aluminum alloy

Friction stir processing (FSP) is an advanced material surface modification technology that is both green and energy-efficient. This technology plays a crucial role in regulating the surface microstructure of alloys and improving alloys’ surface properties. It reaches this through the synergistic effect of non-equilibrium thermodynamic and surface mechanical deformation. In this work, the surface modification of an aluminum alloy was performed using pin-less FSP. Then, the modified surface was analyzed using stress–strain curves, optical microscopy (OM), x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical tests to investigate the impact of spindle velocity on the properties of the modified layer. Results of the study show that after undergoing pinless FSP modification treatment, the surface of the alloy appears bright and flat. The modified layer displays refined grains and numerous dispersed second-phase particles. Furthermore, the grains in the modified layer exhibit a gradient distribution from the surface to the matrix. Regarding the properties, compared to the base material (BM), the yield strength (σ 0.2) and tensile strength (σ b ) of the alloy-modified layer were increased by 34.8% and 29.4%, respectively. The maximum elongation (δ) of the modified coating reached 22.3%. The modified layer exhibits a tough-brittle mixed fracture pattern. Additionally, the modified layer’s corrosion resistance significantly improves. The performance of the modified coating shows the most significant improvement when the spindle speed reaches 1000 rpm.

Influence of bonding temperature on solid-state diffusion bonded joints of AA2219 and Ti-6Al-4V dissimilar alloys—microstructure and mechanical characterisation

Influence of bonding temperature on solid-state diffusion bonded joints of AA2219 and Ti-6Al-4V dissimilar alloys—microstructure and mechanical characterisation

Room Temperature Electrochemical-Shock Synthesis of Solid-Solution Medium-Entropy Alloy Nanoparticles for Hydrogen Evolution.

For millennia, humankind has discovered great benefits in alloying materials. Over the past 100 years, a renaissance in nanoscience has cemented the importance of nanoparticles in a variety of fields ranging from energy storage and conversion to cell biology. While many synthetic strategies exist for nanoparticle and alloy nanoparticle formation, new methods are necessary to create nanoparticles under unprecedented conditions. Here, we demonstrate a simple technique to electrodeposit solid-solution alloy nanoparticles at room temperature. When metal salts of platinum, gold, and palladium are confined to nanodroplets suspended in oil, and then a nanodroplet collides with a sufficiently negative-biased electrode to reduce the metal salts at the mass-transfer limitation, solid-solution alloy nanoparticles form. High-angle annular dark-field scanning transmission electron microscopy and single atom energy dispersive X-ray spectroscopy confirm the solid-solution microstructure of the nanoparticles. The results also confirm the nanodroplet's ability to tune alloy microstructures from amorphous to solid-solution. We further extend our technique by adding salts of silver, which lead to the synthesis of polycrystalline medium-entropy alloys. Finally, we go on to show the application of our midentropy alloys toward renewable and clean energy devices by highlighting their electrocatalytic activity toward hydrogen evolution reaction. Our method is unrivaled in its simplicity and will find applications across various fields of study.

Effect of Composite Scanning Strategy on Forming Quality, Microstructure, and Tensile Properties of Laser Powder Bed Fusion Titanium Alloy

Laser powder bed fusion (LPBF) technology offers significant advantages in manufacturing complex‐shaped titanium alloy components. Traditional scanning strategies, such as zigzag and island scanning, however, often fall short in fabricating parts with variable cross sections. To enhance the forming quality of components featuring combined thin‐walled and bulk structures, a composite scanning strategy is proposed that adapts to the local characteristics of parts. This novel approach is designed to employ both island and zigzag scanning within the same deposition layer, aiming to optimize the balance between porosity and stress distribution. Notably, with a feature transition distance of 4 mm and a scan line offset of 0.67 mm, the specimens achieve a tensile strength of 1311.0 MPa, a yield strength of 1103.0 MPa, and an elongation of 8.8%. This strategy leads to the optimization of defects and a transition in microstructure for combined structural features. These promising outcomes lay the foundation for the intelligent allocation of scanning strategies and the high‐quality formation of complex‐shaped, high‐strength titanium alloy parts.

Effects of laser cladding and plasma nitriding on microstructure and properties of Cu-Al alloy

Effects of laser cladding and plasma nitriding on microstructure and properties of Cu-Al alloy

Effect of Heat Treatment on Microstructure and Aqueous Corrosion Properties of AlCoCrNiFe High Entropy Alloy

Effect of Heat Treatment on Microstructure and Aqueous Corrosion Properties of AlCoCrNiFe High Entropy Alloy

Effects of CeO2 Content on the Microstructure and Mechanical Properties of ZK60 Mg Alloy

Effects of CeO2 Content on the Microstructure and Mechanical Properties of ZK60 Mg Alloy

Impact of Combined Zr, Ti, and V Additions on the Microstructure, Mechanical Properties, and Thermomechanical Fatigue Behavior of Al-Cu Cast Alloys

The effects of minor additions of the transition elements Zr, Ti, and V on the microstructure, mechanical properties, and out-of-phase thermomechanical fatigue behavior of 224 Al-Cu alloys were investigated. The results revealed that the introduction of the transition elements led to a refined grain size and a finer and much denser distribution of θ″/θ′ precipitates compared to that of the base alloy, which enhanced the tensile strength but reduced the elongation at both room temperature and 300 °C. Constitutive analyses based on theoretical strength calculations indicated that precipitation strengthening was the primary mechanism contributing to the strength of both tested alloys at room temperature and 300 °C. The out-of-phase thermomechanical fatigue test results showed that the addition of transition elements caused a slight decrease in the fatigue lifetime, which was mainly attributed to the reduced ductility and higher peak tensile stress at low temperatures. During the fatigue process, the transition element-added alloy exhibited a lower coarsening ratio, indicating higher thermal stability, which mitigated the negative impact of the reduced ductility on the fatigue performance to some extent. Considering their various properties, the addition of Zr, Ti, and V is recommended to improve the overall performance of Al-Cu 224 cast alloys.

Optimizing the corrosion resistance of additive manufacturing TC4 titanium alloy in proton exchange membrane water electrolysis anodic environment

Titanium alloys are commonly used as the bipolar plate material in proton exchange membrane water electrolysis (PEMWE). However, traditional machining methods are difficult to process titanium alloy parts, which further increases the cost of bipolar plates. The wire-arc directed energy deposition (WA-DED) additive manufacturing (AM) technology is low cost and high utilization of material. However, the undesirable microstructure always restricts the performance improvement. In this work, the electrochemical corrosion and passive characteristics of wrought TC4 and WA-DED AM TC4 alloys in the simulated PEMWE anode environment were investigated. The microstructure of AM TC4 alloy was optimized and the corrosion resistance was enhanced by heat treatment. The results indicate that the corrosion resistance of AM TC4 alloy is better than wrought TC4 alloy, and appropriate heat treatment can further improve the stability of passive film. Compared to wrought TC4, Ti −β phase fraction of AM TC4 decreased from 9.6 % to 1.3 %, and the heat treatment further reduced Ti −β phase fraction of AM TC4-850 and AM TC4-1050 alloys to 0.8 % and 0.1 %. The passive film thickness of wrought TC4, AM TC4, AM TC4-850, and AM TC4-1050 alloys calculated with the Power-Law model were 0.5 nm, 1.76 nm, 1.94 nm, and 2.02 nm, respectively. After heat treatment of 1050 °C, AM TC4-1050 alloy exhibited the best corrosion resistance, showing the lowest corrosion current density of 54 μA/cm2 and the lowest passive current density of 19.5 μA/cm2. Moreover, Ti oxide contributed most to the composition of passive film. In AM TC4-1050 alloy, the percentage of Ti oxides was 80.9 %, showing the best corrosion resistance.

Microstructure instability of additively manufactured alloy 718 fabricated by laser powder bed fusion during thermal exposure at 600–1000 ℃

Microstructure and precipitation behavior of alloy 718 produced by laser powder bed fusion (L-PBF) and its recrystallized counterpart were evaluated after thermal exposure at a temperature range of 600–1000 ℃ for up to 1000 h. The as-built 718 featured a microstructure of columnar grains, and dislocation cell structures (DCSs) with chemical segregations (rich in Nb, Ti, Mo and depleted in Cr, Fe) and precipitates (Laves phase and carbonitride). The DCSs remained thermally stable for up to 1000 h at 600 ℃ or 100 h at 700 ℃, but only 10 h at 800 ℃. With the temperature increasing to 900 ℃ and 1000 ℃ for 1 h duration, the DCSs tended to partially disassemble, and the chemical segregations were removed. The chemical segregations at cell boundaries of the as-built 718 promoted the formation of γ′, γ″ and δ phases during aging, leading to a spatially heterogeneous distribution of γ′ and γ″ phases between the cell boundaries and interiors during short exposure time or at lower temperatures. Meanwhile, the coarsening of γ′ and γ″ phases and the phase transformation of γ″ to δ at 700–800 ℃ were facilitated in the as-built 718 compared to the recrystallized ones. A unique precipitation distribution was observed at 700 ℃ that γ′ and γ″ phases precipitated both at the cell boundaries and within cell interiors, while only γ′ formed in the vicinity of cell boundaries. Time-temperature-transformation curves for additively manufactured and recrystallized 718 were constructed based on the microstructure analyses. This study indicates that conventional heat treatment procedures may be suboptimized for additively manufactured 718 in high temperature applications.

Microstructure and radiation shielding capabilities of Al-Cu and Al-Mn alloys

In this study, the microstructure and elemental analysis of aluminum-copper alloy type-2024, Al-2024, and aluminum-manganese alloy type-3003, Al-3003, have been investigated by using a scanning electron microscope (SEM) equipped with Energy dispersive spectroscopy (EDS) detector. Experimental and theoretical radiation shielding studies were performed to assess the radiation shielding capabilities of the studied alloys. Considering the radiation shielding theoretical assessment, some reliable software tools were used, such as Phy-X/PSD, MCNP5, NXCom, and MRCsC. The microstructural observations and results have shown the presence of second phases rich with the main alloying elements in both alloys. Considering Al-2024 alloy, coarse second-phase particles, having a size range of 8–15 μm, were found aligning in lines parallel to the rolling direction, whereas smaller ones, having a size range of 2–8 μm, were found decorated the grain boundaries. Also, dark holes represent the pull-out large particles separated during preparation indicated poor adhesion with the main matrix that could be a result of losing particle coherency with the matrix where the misorientation in-between the atomic planes increase. However, better adhesion of the second-phase particles with the matrix, which were found possessing smaller particle size, have been observed in the Al-3003 alloy indicating good coherency and better manufacturing process for the non-heat-treatable alloy. The second-phase particles in case of Al-2024 alloy were found containing significant content of high-Z elements like Cu with greater volume fraction equals 7.5%. On the other side, Al-3003 alloy has possessed second-phase particles which lack of high-Z elements with only volume fraction equals 3.5%. All the former besides the higher density and content of high-Z elements like copper in Al-2024 alloy in compare to Al-3003 alloy and pure aluminum, led to relatively better radiation shielding capabilities against energetic photons, the highest in the low energy band and decreases with the increase of the photon energy, and slight superiority in the case of fast neutrons with only 3%inc. over pure aluminum. For instance, the radiation protection efficiency (RPE) values dropped from about; 23.2, 21.6, and 20.8% at 0.100 MeV to only 5.7, 5.9, and 5.6% at Eγ = 2 MeV, for; Al-2024, Al-3003, and Al-Pure, respectively."Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.""confirmed"

Effect of Yttrium Addition on Microstructure and Mechanical Properties of Sr-Modified Low-Si Cast Aluminum Alloy

Effect of Yttrium Addition on Microstructure and Mechanical Properties of Sr-Modified Low-Si Cast Aluminum Alloy

Influence of Hot Rolling on Microstructure, Corrosion and Mechanical Properties of Mg–Zn–Mn–Ca Alloy

The effect of hot rolling on the microstructure, mechanical, and corrosion properties of the magnesium alloy 96 wt% Mg–2.3 wt% Zn–0.7 wt% Ca–1 wt% Mn was studied. After heat treatment, the original plates of an as-cast alloy were rolled from a 7 mm thickness to a 0.2 mm thickness at two temperatures—300 or 400 °C. It has been established that increasing the rolling temperature from 300 to 400 °C increases the fraction of recrystallized grains in the microstructure and after rolling at 400 °C, the microstructure is fully recrystallized. The best strength–ductility balance of the alloy was obtained after rolling at 300 °C, with a high total percentage reduction of 93–97%: the yield stress, the ultimate tensile strength, and the elongation averaged at 285 MPa, 310 MPa, and 5%, respectively. The alloy after rolling, annealed at 400 °C, shows improved ductility but lower strength: the yield stress, the ultimate tensile strength, and the elongation were 200 MPa, 260 MPa, and 17%, respectively. The strong dependence of corrosion resistance on respect to rolling direction is observed, which can be reduced after heat treatment. The as-rolled alloy and the heat-treated alloy had low corrosion rates in Hanks’ solution of 0.54 and 0.19 mm/year, respectively.

Study on Microstructure and Properties of AlCoCrFeNi High-Entropy Alloys by Extreme High-Speed Laser Cladding

AlCoCrFeNi HEA powders were cladded onto AISI 1045 steel using EHLA and CLA, respectively. The phase composition, microstructure, micro/nanohardness, and corrosion resistance of the two coatings were compared and analyzed. The results show that the phase structure of AlCoCrFeNi HEA coatings prepared by EHLA and CLA was that of a BCC/B2 phase solid solution. From the bottom to the top, the EHLA-derived AlCoCrFeNi HEA coating experienced evolution in the microstructure of plane crystal, dendrite, and equiaxed crystal. The micro/nanohardness of EHLA-derived coating (~507 HV0.2, 6.716 GPa) is higher than that of CLA-derived coating (~429 HV0.2, 5.778 GPa). The electrochemical test results show that the Ecorr of CLA is −0.527 V and the Icorr of CLA is 1.272 × 10−7 A/cm2, while the Ecorr of EHLA is −0.454 V and the Icorr of EHLA is 1.588 × 10−8 A/cm2, which means that the corrosion resistance of EHLA is better.

Surface microstructure and corrosion resistance characterization of Mg-based amorphous alloys

Surface microstructure and corrosion resistance characterization of Mg-based amorphous alloys

Effect of manufacturing route on microstructure and micromechanical properties of AlCoCrFeNi high entropy alloy

The manufacturing route of a particular metallic alloy profoundly affects its microstructure, as well as mechanical properties. In that respect, the present research investigates the microstructure and microstructure-dependent mechanical properties of the AlCoCrFeNi high entropy alloy (HEA), that was manufactured via two different routes: (i) Atmospheric plasma spraying (APS) in the form of coating on a stainless steel subtract and (ii) vacuum arc melting (VAM) in the form of bulk material. AlCoCrFeNi HEA coating microstructure is composed of a solid solution (Ni) as a matrix, which contains different phases, as well as intermetallics and defects, such as splat boundaries. On the contrary, the microstructure of bulk AlCoCrFeNi HEA alloy is free from any secondary phases, and is homogeneous in nature, which consists of only the solid solution of Ni. The experimental results show that the strength of the bulk HEA (963.14 ± 28.58MPa of yield strength and 1005.58 ± 22.08MPa of compressive strength) is better than that of HEA coating (yield strength of 802.33 ± 43.76MPa and compressive strength of 817.73 ± 43.84MPa). The phase, as well as splat boundaries in the microstructure, are the ‘weakest link’ in the HEA coating, that serves as defect initiation site. As the bulk HEA alloy is free from these ‘weakest link’, thus, deformation of the material is guided through plastic flow of materials, in the terms of the barrelling effect.

Effect of heat treatment on microstructure and mechanical properties of WE43 alloy fabricated by wire arc additive manufacturing

Heat treatment is an effective method to improve the mechanical properties of Wire Arc Additive Manufacturing (WAAM) WE43 alloy. This study investigates the effects of heat treatment on the microstructure and mechanical properties of the WE43 alloy processed by WAAM. The as-deposited samples exhibit a uniform equiaxed crystal structure, with grain size gradually increasing as the number of deposited layers grows. The as-deposited microstructure comprises eutectics and a small amount of cubic phases, and the phase content escalates as the amount of deposited layers increases, influenced by the cumulative effect of multiple thermal cycles. At lower solid solution temperatures (480 ℃ × 8h), most of the eutectic phase remains undissolved. During tensile testing, undissolved eutectics tend to cause stress concentrations, leading to cracks that result in sample fractures, negatively affecting the mechanical properties. At higher solid solution temperatures (520 ℃ × 8h), most of the eutectic dissolves, but abnormal grain coarsening (AGC) in the interlayer fine-grain region occurs, causing a significant reduction in the sample's mechanical properties. After solid solution treatment at 500 °C for 8hours, only a small amount of eutectics remains undissolved, and the AGC phenomenon is not observed, resulting in an optimal solid solution effect. Subsequently, after aging treatment at 225 °C for 18hours, dense nanoscale β′′ phases precipitated within the alloy grains, significantly improving the mechanical properties. The samples achieved optimal performance, with UTS, YS, and EL of 323±15.2MPa, 225±11.3MPa, and 8.4±1.1%, respectively.

Effect of wall thickness on the precipitation behavior, microstructure, electrical conductivity and mechanical properties of copper alloy prepared by electron beam powder bed fusion

Electron beam powder bed fusion (EB-PBF) is one of the most promising technologies for preparing thin-walled copper alloy, because copper alloy have a high energy absorption rate for electron beam, and high preheating temperature can reduce the solidification temperature gradient and reduce the deformation of thin-walled parts. At present, there are few reports on the systematic research work on the EB-PBF of thin-walled CuCrZr alloy parts, and it's impossible to effectively supervise the production of complex thin-walled CuCrZr alloy parts. This work aims to investigate the effect of thickness on the microstructure and mechanical properties of CuCrZr alloy produced by EB-PBF. As the wall thickness decreases from 5.0 mm to 0.3 mm, the grain sizes of the XY and YZ planes decreased from 20.4 μm and 43.1 μm to 14.5 μm and 21.5 μm respectively, and the texture intensity decreased from 16.04 and 23.57 to 7.62 and 10.99. The analysis showed that Cr2O3 nanoprecipitates were precipitated in situ in the sample, and their average size decreased from 65.8 nm to 21.6 nm. Due to the reduction in grain and nanoprecipitate size, the performance of thin-walled samples is significantly enhanced, with yield strength (YS) increasing from 112 MPa to 165 MPa and conductivity increasing from 71.7 %IACS to 86.1 %IACS. Finally, the main contributions to the YS of specimens with different wall thicknesses was discussed. Precipitation strengthening and dislocation strengthening are the main strengthening mechanisms in thin-walled samples, and the gradual refinement of nano-precipitates is the main reason for the improvement of mechanical properties as the wall thickness decreases.

Modeling complex polycrystalline alloys using a Generative Adversarial Network enabled computational platform

Creating statistically equivalent virtual microstructures (SEVM) for polycrystalline materials with complex microstructures that encompass multi-modal morphological and crystallographic distributions is a challenging enterprise. Cold spray-formed (CSF) AA7050 alloy containing coarse-grained prior particles and ultra-fine grains (UFG) and additively manufactured (AM) Ti64 alloys with alpha laths in beta substrates. The paper introduces an approach strategically integrating a Generative Adversarial Network (GAN) for multi-modal microstructures with a synthetic microstructure builder DREAM.3D for packing grains conforming to statistics in electron backscatter diffraction (EBSD) maps for generating SEVMs of CSF and AM alloy microstructures. A robust multiscale model is subsequently developed for self-consistent coupling of crystal plasticity finite element model (CPFEM) for coarse-grained crystals with an upscaled constitutive model for UFGs. Sub-volume elements are simulated for efficient computations and their responses are averaged for overall stress-strain response. The methods developed are important for image-based micromechanical modeling that is necessary for microstructure-property relations.

Effect of heat treatment on the microstructure, mechanical properties and tribological behavior of Ti-45Nb alloy fabricated by laser powder bed fusion

To avoid stress-shielding effects between biomedical implants and human bones, low modulus heat-treated Ti-45Nb specimens fabricated by laser powder bed fusion (LPBF) after annealing heat treatment were studied in this study. The microstructure and mechanical properties of the specimens revealed that (i) the as-built specimen consisted mainly of the β-TiNb phase, and heat treatment did not affect the phase species, demonstrating the thermal stability of the LPBFed Ti-45Nb alloy. (ii) After heat treatment, all the specimens exhibited excellent yield strengths (over 1100 MPa), and low Young's moduli (approximately 80 GPa). (iii) The specimens exhibited excellent wear resistance with the main wear modes of abrasive and adhesive wear and low COF (0.353-0.394) under a load of 20 N.