Multicomponent Alloys Research Articles

Strong and ductile Resinvar alloys with temperature- and time-independent resistivity

Materials with well-defined electrical resistivity that does not change with temperature or time are important in robotics, communication and automation. However, the challenge of designing such materials has remained elusive due to the temperature-dependent electron-phonon scattering. Moreover, resistive electrical conductors used in flexible and mobile systems under high mechanical loads must possess both high strength and ductility. Achieving such multi-properties presents a fundamental challenge. Here, we solve this problem by combining multicomponent alloy design with atomic-scale chemistry tuning. We term the resultant material ‘Resinvar’ alloy, due to its invariable resistivity (148 μΩ·cm) over wide temperature ranges from room temperature to 723 K. The alloy also has high tensile strength (948 MPa) at large tensile elongation (53%). The distorted lattice, chemical short-range order and ordered coherent nanoprecipitates in the material enable the invariant resistivity via promoting temperature-independent inelastic electron scattering, and contribute to the excellent strength-ductility synergy by manipulating dislocation slip.

Stability of the B2 phase among refractory metals

Energy efficiency demands finding new materials for applications at elevated temperatures. Refractory multicomponent alloys with a BCC/B2 microstructure promise to serve as alternatives to the current state-of-the-art, Ni-based superalloys for applications at higher temperatures. With the vast compositional space of these alloys, the first fundamental question is whether the B2 phase can form among refractory metals. In this study, we span through the periodic table to investigate the potential for creating ordered B2 intermetallics among the refractory metals, using first principles calculations, and establish the correlation between the nature of the atomic bonds and stability of the B2 structure. We use our newly developed Multi-Cell Monte Carlo method to explore the extensive compositional space of these alloys, refine the trends in ordering, and pinpoint the most promising combinations for detailed analysis. We discover that B2 phases form exclusively with the inclusion of elements from groups VII and VIII, such as Re, Ru, and Os, and we identify these phases among a total of eleven elements. Further analysis of the electronic structure and bonding characteristics of these B2 systems reveals a pseudogap in the electronic density of states at the Fermi level. This pseudogap is attributed to the hybridization of d orbitals, leading to the formation of strong covalent bonds in the most stable compounds. This finding explains why B2 formation is restricted to elements from groups IV-VIII and V-VII refractory metals.

Mechanical properties of AlCoCrCuFeNi high-entropy alloys using molecular dynamics and machine learning

High-entropy alloys (HEAs) stand out from multi-component alloys due to their attractive microstructures and mechanical properties. In this investigation, molecular dynamics (MD) simulation and machine learning (ML) were used to ascertain the deformation mechanism of AlCoCrCuFeNi HEAs under the influence of temperature, strain rate, and grain sizes. First, the MD simulation shows that the yield stress decreases significantly as the strain and temperature increase. In other cases, changes in strain rate and grain size have less effect on mechanical properties than changes in strain and temperature. The alloys exhibited superplastic behavior under all test conditions. The deformity mechanism discloses that strain and temperature are the main sources of beginning strain, and the shear bands move along the uniaxial tensile axis inside the workpiece. Furthermore, the fast phase shift of inclusion under mild strain indicates the relative instability of the inclusion phase of hexagonal close-packed (HCP). Ultimately, the dislocation evolution mechanism shows that the dislocations are transported to free surfaces under increased strain when they nucleate around the grain boundary. Surprisingly, the ML prediction results also confirm the same characteristics as those confirmed from the MD simulation. Hence, the combination of MD and ML reinforces the confidence in the findings of mechanical characteristics of HEA. Consequently, this combination fills the gaps between MD and ML, which can significantly save time, human power, and cost to conduct real experiments for testing HEA deformation in practice.

Microstructural evolution and precipitation behavior of multicomponent Al83Mg5Si5Cu5Li2 alloy

We investigated the microstructural evolution and precipitation behavior of a new multicomponent Al83Mg5Si5Cu5Li2 alloy using transmission electron microscopy and atom-probe tomography. As-cast alloy consists of θ-Al2Cu, Mg2Si, Q-Al5Cu2Mg8Si6, and AlLiSi phases. Solution treatment causes the formation of the Q-Al5Cu2Mg8Si6 phase, and slow furnace cooling causes the formation of θ-Al2Cu particles in the Al matrix, which depletes solute atoms. Nanoscale Cu/Si/Mg-rich solute clusters are formed during natural aging, contributing to an excellent age-hardening response.

Modified Cu active sites by alloying for efficient electrocatalytic reduction CO2 to CO

Transition metals like Au, Ag, and Cu have been reported to be quite active for CO2 reduction. In this study, we use density functional theory (DFT) calculation to investigate the electronic structure and catalytic performance of Au, Ag, Cu and their alloys for CO2 reduction reaction (CO2RR). Theoretical calculations identified the combination of Ag, Cu, and Au in a face-centered cubic (fcc) alloy as an outstanding electrocatalyst for CO2 reduction to CO, with Cu as the active site. The d-orbital projected density of state (PDOS) profile suggests that alloying alters the electronic structure of the Cu site, thereby affecting the Gibbs free energy change for the formation of *COOH intermediate (ΔG*COOH). To demonstrate the theoretical prediction experimentally, we employ a top-down dealloying approach to synthesize a nano-porous structured AgCuAu alloy (NP-Ag5Cu5Au5). Electrochemical experiments validate that the ternary alloy catalyst is clearly better than unary and binary catalysts, showing a Faradaic efficiency (FE) for CO over 90% across a broad potential range of 0.6 V, with a peak of approximately 96% at −0.573 V vs. RHE. This study underscores the potential of multi-component alloys in CO2RR and establishes a theoretical basis for designing efficient catalysts for CO2 utilization.

Highly reversible Mg-containing multicomponent high-entropy alloys for electrochemical hydrogen storage applications

Magnesium containing high entropy alloys have gained attention recently as a potential material for hydrogen storage applications. In this work, five non-equiatomic compositions of MgTiZrNiAl HEAs were synthesized using a high-energy ball milling technique and electrochemically characterized for hydrogen storage performance. The concentrations of Mg and other constituent alloying elements are critical to achieving good storage capacity and other hydrogen storage properties. Interestingly, higher Mg atomic percent (40–50 at%) in the HEA matrix showed high gravimetric capacity, and increasing the constituent element like Ni has significantly enhanced the overall storage capacity, kinetics, and thermodynamic properties. Overall, 1 wt% of hydrogen was electrochemically stored with high reversibility, improved hydrogen diffusion coefficient, and anticorrosion ability.

An order-disorder core-shell strategy for enhanced work-hardening capability and ductility in nanostructured alloys

Nanocrystalline metallic materials have the merit of high strength but usually suffer from poor ductility and rapid grain coarsening, limiting their practical application. Here, we introduce a core-shell nanostructure in a multicomponent alloy to address these challenges simultaneously, achieving a high tensile strength of 2.65 GPa, a large uniform elongation of 17%, and a high thermal stability of 1173 K. Our strategy relies on an ordered superlattice structure that excels in dislocation accumulation, encased by a ≈3 nm disordered face-centered-cubic nanolayer acting as dislocation sources. The ordered superlattice with high anti-phase boundary energy retards dislocation motions, promoting their interaction and storage within the nanograins. The disordered interfacial nanolayer promotes dislocation emission and effectively accommodates the plastic strain at grain boundaries, preventing intergranular cracking. Consequently, the order-disorder core-shell nanostructure exhibits enhanced work-hardening capability and large ductility. Moreover, such core-shell nanostructure exhibits high coarsening resistance at elevated temperatures, enabling it high thermal stability. Such a design strategy holds promise for developing high-performance materials.

Design, Synthesis, and Characterization of Al‐Containing Multicomponent Alloys for Hydrogen Storage and Compression

AbstractIn this paper, compositions within the TiZrAlCrMn, TiZrAlCrFe, and TiZrAlMnFe alloy systems that form the C14 Laves phase are investigated. The design, synthesis, structural, and hydrogen storage characterizations for an equiatomic and a non‐equiatomic composition for each alloy system are presented. Additionally, the further development of a thermodynamic method for the calculation of pressure‐composition‐isotherms (PCIs) is presented of C14 Laves phase alloys that absorb hydrogen by solid solution. Overall, the results shown in this paper indicate that Al‐containing multicomponent alloys can present promising hydrogen storage performance under high pressures. Nonetheless, high concentrations of aluminum in highly concentrated (equiatomic) alloys can have a negative impact on the hydrogenation properties. The Ti0.29Zr0.05Al0.05Cr0.26Mn0.35 composition showed promising hydrogenation/dehydrogenation properties. The gravimetric capacity of this alloy is ≈1.76 wt.% H2 and the PCIs measured indicate that this material has potential for high‐pressure hydrogen storage and compression applications. The use of the presented thermodynamic model for the design of multicomponent alloys is suggested.

Fine grains, dispersed phases and strong crystal defect interactions inducing excellent strength-ductility synergy in powder sintered Cu–18Sn-0.3Ti alloy via hot extrusion and solution treatment

In order to prepare the Cu–18Sn-0.3Ti alloy with excellent mechanical properties to realize the favorable collaborative deformation of Cu–18Sn-0.3Ti alloy and Nb in the preparation process of Nb3Sn superconducting wires by bronze method, the hot extrusion process of the Cu–18Sn-0.3Ti alloy prepared by Direct Current assisted Hot Pressed sintering based on micron atomized spherical alloy powders was systematically investigated by the combination of experiments and finite element simulation in this work. The ultimate tensile strength, yield strength and elongation can reach 683.5 MPa, 414.3 MPa and 33.3 %, respectively, through the optimization of hot extrusion parameters and subsequent solution treatment. The results show that hot extrusion with high strain rate induced the formation of fine α grains and dispersed δ phases. Especially, strong dislocations-annealing twins (ATs) interaction occurred, which was manifested as the pile-up of dislocations at twin boundaries of ATs, slippage of dislocations in multiple directions inside ATs and storage of dislocations inside ATs. Meanwhile, the high strain rate induced the formation of deformation twins inside partial grains. The grain refinement of α matrix, formation of dispersed δ phases and strong interactions of crystal defects were the main reasons for the strength-ductility enhancement of hot extruded samples, and laid an excellent microstructure foundation for further improving the mechanical properties of alloy by subsequent solution treatment. The results not only describe a feasible method for simultaneously enhancing the strength and ductility of Cu–18Sn-0.3Ti alloy, but also provide a theoretical guidance for the strength-ductility enhancement of multicomponent alloys.

Enhanced torsional strength and plasticity synergy of multi-component alloy via multi-level gradient structures

This study investigates an approach to enhance the strength and torsional angle, as well as analyze the microstructure and mechanical properties of a multi-component Cu-based alloy. A unique gradient-structured alloy is successfully synthesized by subjecting CuAl10Fe5Ni4Mn0.23 to high-frequency large torsional deformation. The results showed that the multi-level gradient structure due to high-frequency deformation significantly enhances the torsional strength of CuAl10Fe5Ni4Mn0.23 alloy. With a torsional rate of 120°/min and a maximum torsional angle achieved at 40°, after 200 cycles, compared to non-torsional samples, the torsional strength increased by 75.69 % and the torsion angle also increased by 38.36 %. The combination of the alloy primary structures along with gradient structures forms a new microband structure that synergistically improves the mechanical properties of multi-component alloys. The proposed large torsion deformation alters the structure of multi-component alloys, resulting in a gradient structure that simultaneously enhances both strength and plasticity, resolving current reciprocal dilemmas between these two factors.

Synthesis, characterization, and azo dye degradation performance of mechanically alloyed Mg65Cu20Y13La2 nanocrystalline powders

This research describes the synthesis of the multicomponent Mg65Cu20Y13La2 alloy by mechanical alloying (MA) to investigate the influence of milling times on the microstructure of alloy and degradation performance of methyl orange. The structural evolution of this alloy was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDX) techniques. The thermal behavior of the alloys was investigated by differential scanning calorimetry (DSC). The crystallite size of the Mg65Cu20Y13La2 alloys was calculated using the Debye Scherrer equation with broadening of the XRD peaks. The methyl orange degradation efficiencies of the Mg65Cu20Y13La2 alloys were evaluated by using ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and gas chromatography–mass spectrometry (GC–MS) techniques. The XRD and SEM results showed that the microstructure of the powders changed during MA. After 10 h milling time, three intermetallic phases were obtained as Mg2Cu2La, Mg24Y5, and Mg2Cu. The results also showed that a solid solution phase, α-Mg(Cu, Y, La), with an average crystallite size 21 nm was formed after 100 h milling time. DSC trace of the Mg65Cu20Y13La2 powders showed two exothermic peaks for the 10 h milling time, while it did not show any peaks for the 100 h milling time. Photocatalytic decomposition of the methyl orange solution by the Mg65Cu20Y13La2 alloy was evaluated by UV–Vis spectra with a decrease in absorbance at a wavelength of 465 nm. After a 20 min exposure, UV–Vis, FT-IR, and GC–MS analysis showed that the methyl orange samples were almost completely degradation by using the Mg65Cu20Y13La2 powders. The Mg65Cu20Y13La2 alloy exhibits a good reusability of 92% by the four cycle and a high efficiency was achieved in all the pH values in the range of 5–9. The results prove that the Mg65Cu20Y13La2 alloy is an efficient and promising material for dyeing wastewater treatment.

The role of zinc addition on the microstructural evolution and mechanical properties of wire-arc directed energy deposited Mg-Gd-Y-(Zn)-Zr alloys

Wire-arc directed energy deposition (WA-DED) demonstrates significant potential in the rapid and free forming of high-strength magnesium rare-earth (Mg-RE) alloys. This highlights a growing demand for tailored wire alloy compositions to promote engineering applications of this technology. In this work, the role of zinc addition on WA-DED processed Mg-Gd-Y based alloys has been thoroughly investigated by utilizing Mg-6Gd-3Y-0.5Zr (wt.%, GW63K) and Mg-6Gd-3Y-0.5Zn-0.5Zr (wt.%, GWZ631K) alloy wires as model materials. The microstructure evolution of these two alloys during deposition and heat treatment is revealed by multi-scale microstructure characterization techniques. The influences of Zn addition on mechanical properties of these deposited alloys are investigated comparatively. Obtained results indicate that addition of Zn element into Mg-Gd-Y based alloys promotes phase transformation between eutectic phases and long period stacking order (LPSO) phases during the WA-DED deposition process owing to the multiple thermal cycling. More importantly, the addition of Zn element increases the tendency of solidification shrinkage of the deposited metal. During high-temperature solid solution treatment, the presence of Zn is conducive to improving the thermal stability of the as-deposited grain boundaries and thus suppressing grain coarsening. After optimized T6 treatments, the strength of GW63K alloys increases to 374±7MPa, and is obviously higher than that (315±6MPa) of GWZ631K alloys. The addition of Zn element weakens the precipitation strengthening effect. This can be attributed to the formation of LPSO phases, which consumes a substantial amount of RE elements, and in turn decreases the density of aging precipitated nanoscale β´ phases. This work promotes the understanding of the non-equilibrium solidified microstructure evolution of multi-component Mg-RE alloys and guides the optimization of alloy composition of WA-DED specific wire materials.

Small dataset machine-learning approach for efficient design space exploration: engineering ZnTe-based high-entropy alloys for water splitting

Aiming toward a sustainable energy era, the design of efficient photocatalysts for water splitting by engineering their band properties has been actively studied. One promising avenue for the band engineering of active photocatalysts is the use of solid-solution alloying. However, the enormous possible configurations of multicomponent alloys hinders the experimental screening of this multidimensional material space, providing an opportunity for machine learning (ML) approaches to help accelerate the discovery of new multicomponent alloy materials. A conventional prerequisite for ML approaches is a large database of accurate material properties, which may require exhaustive computational and/or experimental resources. This study demonstrates that the screening of solid-solution alloys (up to hexanary systems) can be performed using a small database to minimize (and optimize) the number of high-level computational calculations. Specifically, we use ZnTe-based alloys as a prototypical example and employ a secure independent screening and sparsifing operator with the recently developed agreement method (α-method). Furthermore, we discuss and propose design routes to determine the optimal solid-solution ZnTe-based alloys for photoassisted water-splitting reactions.

CHEMICAL COMPOSITION OF REMAINS OF METAL RAW MATERIALS ON THE WALLS OF LYCEUM FORMS AND CRUCCILES AS A SOURCE ON THE HISTORY OF JEWELERY PRODUCTION IN THE TERRITORY OF NORTH AND CENTRAL BELARUS IN THE X–XVIII CENTURIES

The article presents the results of a study of the chemical composition of the remains of metal raw materials preserved on the surface of casting devices of the 10th–18th centuries, found on the territory of Northern and Central Belarus. The author has established that the main alloys of non-ferrous metals fixed on the walls of pots and crucibles are multicomponent and lead brass, which allows them to be considered as a distinctive feature of local non-ferrous metalworking. It is noted that lead brasses are most typical for industrial complexes of the 10th–13th centuries, and com-plex copper-zinc alloys are found in crucibles from a workshop of the 17th–18th centuries. The author also determined that some of the clay and stone foundry molds were used for casting metal raw materials. It was established that mainly copper-zinc and multicomponent alloys were melted in the molds.

Ab initio simulation of the dynamic shock response of single crystal and lightweight multicomponent alloy

The dynamic response of shock wave impact on single crystal aluminium and lightweight multicomponent alloy Al-Cu-Li-Mg is simulated by using the combination of Ab initio Molecular Dynamics (AIMD) and Multi-Scale Shock Technique (MSST), with the analysis carried out at the atomic/electronic levels. The simulation is verified by comparing the particle velocity of single crystal obtained in this work with the data in literature. The shock compression process not only involves the migration of atoms, but also is related to electronic transition. Two stages could be found in the shock compression process: oscillatory compression of the crystal cell and oscillatory migration of the atoms. The crystal structure of the multicomponent alloy could be disordered even at low shock speed, due to the difference in the ability to migrate between different kinds of atoms. As the sample is shock-compressed, the contribution proportion of crystal orbitals shows a sharp decrease for D orbital, while it increases significantly for S orbital and P orbital. The electron structure shows a quicker response to the shock wave compression process than the crystal structure. The orbital contribution from P orbital of the crystal is mainly due to the P orbital of Al atoms, while the orbital contribution from D orbital of the crystal is mainly due to the D orbital of Cu atoms. Total Density of States (TDOS) is mainly contributed by the Projected Density of State (PDOS) of Cu atoms in the occupied state of energy levels, while it is close to the PDOS of Al atoms in the non-occupied state of energy levels.

Effect of Directional Partial Ordering in L12 CSRO Domains on Dislocations Behavior in FCC Multicomponent Alloys via 4D-STEM Diffuse-Scattering Fluctuation and Correlation Analysis

Effect of Directional Partial Ordering in L12 CSRO Domains on Dislocations Behavior in FCC Multicomponent Alloys via 4D-STEM Diffuse-Scattering Fluctuation and Correlation Analysis

Empowering multicomponent alloys with unique nanostructure for exceptional oxygen evolution performance through self-replenishment

Empowering multicomponent alloys with unique nanostructure for exceptional oxygen evolution performance through self-replenishment

An integrated modeling framework with open architecture for phase field simulation of multi-component alloys

An integrated modeling framework (PanPhaseField) has been developed, which enables a direct and fast coupling between CALPHAD calculations and large-scale phase field simulations for multi-component alloys. It adopts an open architecture allowing for integration of user-defined phase field models in a plug-and-play manner by taking full advantage of the user-friendly graphical interface of Pandat software. The developed modeling platform becomes an enabling tool that can be used to simulate the evolution of spatially varying microstructures of industrial complex alloys for various engineering applications.

Next-generation multicomponent SMAs: leveraging HEA empirical parameters

Empirical rule calculation, commonly used for phase selection of high entropy alloys (HEAs), provides valuable guidelines for designing multicomponent solid solutions. It is unknown whether the technique can offer a similar design strategy for multicomponent intermetallics that undergo B2−B19′ transformation. Establishing such guidelines can significantly accelerate the pace of discovery for new shape memory alloys (SMAs) by narrowing down the search area within the vast compositional design space of multicomponent alloys. In this study, we compiled hundreds of data on medium and high-entropy NiTi-based alloys exhibiting B2−B19′ transformation. Our objective was to construct a more comprehensive Ω−δ map and locate multicomponent SMAs on it. Additionally, we conducted a thorough analysis to establish a correlation between transformation temperatures and compositional features in medium and high-entropy SMAs (ME and HE-SMAs). This correlation can be leveraged to design SMAs with targeted transformation temperatures.

Thermal and Microstructural Characterization of the Multicomponent Alloy Al33wt%Cu1wt%Ni-1.2wt%Ta Solidified with Transient Heat Flow

Thermal and Microstructural Characterization of the Multicomponent Alloy Al33wt%Cu1wt%Ni-1.2wt%Ta Solidified with Transient Heat Flow