Properties Of Alloys Research Articles

Comparative Study of the Tensile Properties of a Zircaloy-4 Alloy Characterized by Mesoscale and Standard Specimens

The accuracy and reliability of small-scale mechanical tests remain doubtful due to significant dependence of the obtained mechanical properties on specimen size. Mesoscale tensile tests with specimen sizes ranging from 10 μm to 1 mm are capable of obtaining bulk-like properties but are rarely applied to hexagonal close-packed metals. In this study, well-designed comparative tensile tests were carried out on a Zircaloy-4 alloy with a grain size of 4 μm using femtosecond laser-machined mesoscale specimens with a thickness of about 60 μm, sub-sized specimens with a thickness of about 1.3 mm, and standard specimens with a thickness of 4 mm. The quantitative results revealed that irrespective of the small specimen dimensions, the yield strength, tensile strength, and tensile ductility are only approximately 10.4%, 5.2%, and 13% lower than those of the standard specimens, respectively. This clearly demonstrates that the mechanical properties can be assessed with satisfactory accuracy by mesoscale tensile tests. The comparatively greater deviation of the yield strength at the mesoscale arises from the disappearance of yield point behavior, while the reduced tensile ductility is associated with the larger volume fraction of surface grains. The surface grains are characterized by more surface dislocation sources and deform with weaker constraints from neighboring grains, leading to smooth plastic yielding and slightly reduced strain hardening at the mesoscale.

Investigation on phase formation and thermoelectric transport properties of CoTe2-CoSe2 solid solution alloys.

CoTe2 and CoSe2 alloys have garnered considerable attention in thermoelectric applications due to their high electrical conductivity, tunable electronic properties, and potential for high power factors. In this study, the phase formation behavior and thermoelectric transport properties of a CoTe2-CoSe2 solid solution alloy were investigated by synthesizing a series of Co(Te1-xSex)2 compositions, where x = 0, 0.25, 0.50, 0.75, and 1.0. For x = 0, 0.25, and 0.50, the orthorhombic phase of CoTe2 was observed, while for x = 0.75, the orthorhombic phase of CoTe2 and cubic phase of CoSe2 coexisted. Up to x = 0.50, the power factor decreased slightly as the Hall mobility and the density-of-state effective mass decreased. The total thermal conductivity decreased as x increased to 0.50, owing to a decrease in the electronic and lattice thermal conductivity. Despite the decrease in total thermal conductivity, no significant increase in zT values was observed in the range of x = 0.25-0.50 due to a more pronounced decrease in the power factor. Nevertheless, cubic phase CoSe2 exhibited higher power factors and thus higher zT of 0.13 at 700K. Further analysis based on single Kane band model suggests that significant enhancement in the power factor and zT could be achieved by reducing the carrier concentration from ∼1021 to ∼1019 cm-3 for all compositions.

WxMo1‐xO2 Nanocrystals Synthesized by WSe2‐Assisted Chemical Vapor Deposition Method

Transition metal oxide alloys, with tunable stoichiometric ratio, have garnered significant attention due to their unique electronic structure and diverse chemical properties. However, synthesis of micron‐scale, single‐crystalline transition metal oxide alloys remains a challenge due to their unique alloy structure and stringent synthesis conditions. Herein, a WSe2‐assisted chemical vapor deposition method is reported for synthesizing WxMo1‐xO2 nanocrystals with various dimensions: nanorods, nanoplates, and nanodots. The microscopic (optical microscope, atomic force microscope, and scanning electron microscope) images reveal that the nanocrystals have well‐defined non‐layered polyhedral structures. The elemental composition is confirmed by Raman spectroscopy and energy dispersion spectroscopy. The change in phonon symmetry in nanorods and the blue shift of Raman peaks in nanocrystals demonstrate the significant role of the quantum confinement effect. The spatial distribution of the various dimensional nanocrystals provides insights into the possible growth mechanism and the key role of the WSe2 in growth. The WSe2‐assisted growth strategy for alloyed nanocrystals can expand the transition metal oxide alloy material library and offer a platform for exploring additional properties of transition metal oxide alloys.

Effects of Red Mud on Microstructures and Heat Resistance of ZL109 Aluminum Alloy

The effects of red mud on the microstructures and high-temperature tensile properties of the ZL109 aluminum alloy have been investigated. Red mud/ZL109-based composite materials with added red mud (a major byproduct of the aluminum industry), which has been coated with nickel by chemical deposition, have been prepared through gravity casting. The results show that the addition of red mud promotes the alloy’s microstructure and helps to uniformly distribute the eutectic silicon. It also increases the content of heat-resistant phases, such as the Q-Al5Cu2Mg8Si6 and γ-Al7Cu4Ni phases. These changes significantly enhance the alloy’s high-temperature tensile properties. The alloy with 1% (wt.%) red mud exhibits the best tensile strength at both room temperature and 350 °C, reaching 295.4 MPa and 143.3 MPa, respectively. The alloy with 1.5% (wt.%) red mud demonstrates excellent performance at 400 °C, achieving a tensile strength of 86.2 MPa through the cut-through method and Orowan mechanism. As a reinforcing material, red mud not only improves the high-temperature resistance of the aluminum alloy but also provides a way to recycle industrial waste. This study offers a new way to address the red mud waste problem and helps develop high-performance, heat-resistant aluminum alloys. It shows the potential of these alloys in high-temperature applications.

Localized Heating Assisted Laser Shock Peening without Coating Enhances Mechanical Properties of Ti6Al4V Alloys

Room-temperature laser shock peening without coating (RT-LSPwoC) is the mainstream method for surface strengthening, yet it induces tensile residual stress on the surface during rapid heating and cooling. Warm LSPwoC, combining the benefits of dynamic strain aging and LSPwoC, exhibits higher performance than RT-LSPwoC. However, overall high-temperature is time- and resource-consuming, and it is prone to causing thermal stress relaxation during processing, making it unsuitable for large-scale applications. In this paper, a novel localized heating assisted LSPwoC (LHA-LSPwoC) method, utilizing a continuous wave laser for local heating, is proposed. Additionally, the deep physics-informed neural network model, embedded with physical formulas, is designed for process optimization. It enables rapid and accurate responses for an extensive number of cases (40 cases with an average deviation below 1%), overcoming the drawbacks of traditional numerical simulations that are time-consuming and difficult to efficiently handle numerous cases. Compared to RT-LSPwoC, LHA-LSPwoC samples have higher dislocation density and higher grain refinement, demonstrating higher hardness and residual stress, particularly superior fatigue performance. The mechanism of LHA-LSPwoC is discussed, and thermally coupled finite element simulations and molecular dynamics calculations are conducted to provide theoretical support. The proposed method is cost-effective and flexible, showing outstanding potential for industrial applications.

Influence of scanning strategies on microstructure, texture and mechanical properties of Ti65 high-temperature titanium alloy by laser deposition manufacturing

Influence of scanning strategies on microstructure, texture and mechanical properties of Ti65 high-temperature titanium alloy by laser deposition manufacturing

The effect of structural evolution on the magnetocaloric properties of Cu-added GdHoErNi high-entropy alloys

The effect of structural evolution on the magnetocaloric properties of Cu-added GdHoErNi high-entropy alloys

The influence of deformation-dependent prior chip boundary on microstructure and tensile properties in a solid-state recycled AA6063 aluminum alloy

The influence of deformation-dependent prior chip boundary on microstructure and tensile properties in a solid-state recycled AA6063 aluminum alloy

Microstructure evolution and mechanical properties of GH3535 alloy produced by wire arc additive manufacturing

Microstructure evolution and mechanical properties of GH3535 alloy produced by wire arc additive manufacturing

Improvement of the mechanical properties of Fe-based amorphous alloy coating by the loading direct current

Improvement of the mechanical properties of Fe-based amorphous alloy coating by the loading direct current

Optimizing microstructure and minimizing defects in laser-arc hybrid additive manufacturing of Al-Cu alloy: the role of laser mode

Recently, laser-arc hybrid additive manufacturing (LAHAM) has emerged as a transformative method for producing lightweight aluminum alloys, valued for its advantageous surface quality and mechanical properties. In this study, the effect of various laser modes on macro morphology, defect formation, microstructure evolution, and mechanical properties of Al-Cu alloy were investigated. At a laser power threshold of 1.5 kW, the transition from conduction mode to keyhole mode was observed. When the keyhole formed, the molten metal exhibited enhanced fluidity, resulting in smoother surfaces and more uniform spreading. As laser power increased, although hydrogen-induced pores (HIP) were notably reduced, the keyhole-induced pores (KIP) began to appear. During subsequent depositions, the intense reheating effects from laser facilitated a transformation from reticular eutectics (RE) along grain boundaries to granular eutectics (GE). Additionally, recrystallization and formation of Σ3 coincidence site lattice (CSL) boundaries were restricted due to the reduced residual stress caused by moderating cooling rates, alleviating stress concentration near pores during deformation. Therefore, optimal results were achieved in conduction mode at a laser power of 1 kW, achieving highest tensile strengths of 269.5 MPa and 260.1 MPa, and elongations of 19.6% and 13.8% in horizontal and vertical directions, respectively.

Chemical short-range order and its influence on selected properties of non-dilute random alloys

In recent years, non-dilute random alloys (NDRAs) have been gaining interest as promising materials for high-temperature structural applications due to their unique ability to form solid solution phases that portray exceptional mechanical properties and resilience under extreme conditions. This study deals with the effects of chemical short-range order (CSRO) on selected material properties including lattice parameters, lattice distortion (LD), unstable stacking fault energy (USFE), and melting points (MPs). The main body of this study is on 21 ternary alloys, where the interatomic interactions are described by an embedded-atom method potential. Our results demonstrate that random structures generally exhibit larger lattice parameters and greater LD compared to CSRO structures, while CSRO structures possess higher USFEs and MPs. Furthermore, there is no discernible pattern in the segregation of the same and different atom pairs in the NDRAs, as revealed by the notably varying local ordering or segregation for most of them. Last, the effects of interatomic potential and the number of constituent elements are studied using other interatomic potentials and/or non-ternary systems, suggesting that our finding is consistent across different potentials/alloys.

Evolution of microstructure, mechanical and functional properties in cold-rolled TiNiCuNb alloy after post-deformation annealing

Evolution of microstructure, mechanical and functional properties in cold-rolled TiNiCuNb alloy after post-deformation annealing

Fabrication and tribological properties of bionic surface texture self-lubricating 60NiTi alloy via selective laser melting and infiltration

Due to its low elastic modulus, low density, non-magnetic and good lubricity, 60NiTi alloy is considered a novel fourth-generation aerospace bearing material. In this paper, 60NiTi biomimetic surface textured self-lubricating composites were fabricated by selective laser melting (SLM) and high-temperature fusion infiltration (HTFI). The effects of different slit widths (NTD), edge lengths (NTA), and soft metal Sn-Pb-Ag (SPA) infiltration on its tribological properties were studied. The results show that the NTA-SPA structural samples with medium texture density (ρ=16%) promoted the diffusion of the lubricant phase to the friction surface, resulting in a complete lubricant film. The COF stabilized at 0.2, and the wear rate decreased to 0.56×10-3 mm3/Nm, providing a more stable self-lubrication effect compared to the NTD-SPA sample.

Refined microstructure and enhanced properties of CuCr50 alloys produced via electron beam powder bed fusion

Refined microstructure and enhanced properties of CuCr50 alloys produced via electron beam powder bed fusion

Enhanced dynamic compression properties of a low density near-α titanium alloy associated with deformation induced laminated microstructure and dynamic segregation

Enhanced dynamic compression properties of a low density near-α titanium alloy associated with deformation induced laminated microstructure and dynamic segregation

The effect of cryogenic treatment followed by pulsed arc treatment on the microstructure and mechanical properties of TC4 titanium alloy

The effect of cryogenic treatment followed by pulsed arc treatment on the microstructure and mechanical properties of TC4 titanium alloy

Chemical ordering enhancing mechanical properties of Nb25Ti35V5Zr35Alx refractory high-entropy alloys

Chemical ordering enhancing mechanical properties of Nb25Ti35V5Zr35Alx refractory high-entropy alloys

Strategies for optimizing mechanical properties of refractory high entropy alloys induced by solid solution strengthening mechanism

Strategies for optimizing mechanical properties of refractory high entropy alloys induced by solid solution strengthening mechanism

Effect of Trace Sc Addition on Microstructure and Mechanical Properties of Al-Zn-Mg-Cu-Zr Alloy

Transition element microalloying is important for improving the properties of Al-Zn-Mg-Cu alloys. Nevertheless, along with its high costs, increasing Sc content generates a harmful phase, limiting the strength of the alloy. In this experiment, we reduced the amount of Sc added to a Zr-containing Al-Zn-Mg-Cu alloy by one order of magnitude. The microstructure and mechanical properties of the alloys were studied by means of tensile tests, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The findings indicate that the alloys’ mechanical properties were progressively enhanced with the increase in Sc content from 0 to 0.04%. After adding 0.04% Sc, the tensile strength and yield strength of the Al-Zn-Mg-Cu-Zr-Sc alloy increased by 20.9% and 24.3%, reaching 716 MPa and 640 MPa, respectively, and the elongation decreased, but still reached 12.93%. The strengthening mechanisms of the trace addition of Sc are fine grain strengthening and precipitate and disperse strengthening, and Al3(Sc, Zr) particles hinder the dislocation and grain boundary movement. Drawing on insights from other studies on Sc microalloying in Al-Zn-Mg-Cu alloys, this experiment successfully reduced the amount of Sc added by an order of magnitude, the alloys properties were improved, and the effect of strengthening remained good.