Design of low-alloying and high-performance solid solution-strengthened copper alloys with element substitution for sustainable development

Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-speed rail contact wires,electronic component connectors,and other devices.Overcoming the contradiction between low alloying and high performance is an important challenge in the development of solid solution-strengthened copper alloys.Taking the typical solid solution-strengthened alloy Cu-4Zn-1Sn as the research object,we proposed using the element In to replace Zn and Sn to achieve low alloying in this work.Two new alloys,Cu-1.5Zn-1Sn-0.4In and Cu-1.5Zn-0.9Sn-0.6In,were designed and prepared.The total weight percentage content of alloying elements decreased by 43%and 41%,respectively,while the product of ultimate tensile strength(UTS)and electrical conductivity(EC)of the annealed state increased by 14%and 15%.After cold rolling with a 90%reduction,the UTS of the two new alloys reached 576 and 627MPa,respectively,the EC was 44.9%IACS and 42.0%IACS,and the product of UTS and EC(UTS×EC)was 97%and 99%higher than that of the annealed state alloy.The dislocations proliferated greatly in cold-rolled alloys,and the strengthening effects of dislocations reached 332 and 356 MPa,respectively,which is the main reason for the considerable improvement in mechanical properties.

Design of high-temperature superconductors at moderate pressures by alloying AlH3 or GaH3

Since the discovery of hydride superconductors,a significant challenge has been to reduce the pressure required for their stabilization.In this context,we propose that alloying could be an effective strategy to achieve this.We focus on a series of alloyed hydrides with the AMH_(6)composition,which can be made via alloying A15 AH_(3)(A=Al or Ga)with M(M=a group IIIB or IVB metal),and study their behavior under pressure.Seven of them are predicted to maintain the A15-type structure,similar to AH_(3)under pressure,providing a platform for studying the effects of alloying on the stability and superconductivity of AH_(3).Among these,the A15-type phases of AlZrH_(6)and AlHfH_(6)are found to be thermodynamically stable in the pressure ranges of 40–150 and 30–181 GPa,respectively.Furthermore,they remain dynamically stable at even lower pressures,as low as 13 GPa for AlZrH_(6)and 6 GPa for AlHfH_(6).These pressures are significantly lower than that required for stabilizing A15 AlH3.Additionally,the introduction of Zr or Hf increases the electronic density of states at the Fermi level compared with AlH3.This enhancement leads to higher critical temperatures(Tc)of 75 and 76 K for AlZrH_(6)and AlHfH_(6)at 20 and 10 GPa,respectively.In the case of GaMH_(6)alloys,where M represents Sc,Ti,Zr,or Hf,these metals reinforce the stability of the A15-type structure and reduce the lowest thermodynamically stable pressure for GaH_(3) from 160 GPa to 116,95,80,and 85 GPa,respectively.Particularly noteworthy are the A15-type GaMH_(6)alloys,which remain dynamically stable at low pressures of 97,28,5,and 6 GPa,simultaneously exhibiting high Tc of 88,39,70,and 49 K at 100,35,10,and 10 GPa,respectively.Overall,these findings enrich the family of A15-type superconductors and provide insights for the future exploration of high-temperature hydride superconductors that can be stabilized at lower pressures.

Magnesium alloys as alternative anode materials for rechargeable magnesium-ion batteries:Review on the alloying phase and reaction mechanisms

Magnesium-ion batteries(MIBs)are promising candidates for lithium-ion batteries because of their abundance,non-toxicity,and favorable electrochemical properties.This review explores the reaction mechanisms and electrochemical characteristics of Mg-alloy anode materials.While Mg metal anodes provide high volumetric capacity and dendrite-free electrodeposition,their practical application is hindered by challenges such as sluggish Mg^(2+)ion diffusion and electrolyte compatibility.Alloy-type anodes that incorporate groups XIII,XIV,and XV elements have the potential to overcome these limitations.We review various Mg alloys,emphasizing their alloying/dealloying reaction mechanisms,their theoretical capacities,and the practical aspects of MIBs.Furthermore,we discuss the influence of the electrolyte composition on the reversibility and efficiency of these alloy anodes.Emphasis is placed on overcoming current limitations through innovative materials and structural engineering.This review concludes with perspectives on future research directions aimed at enhancing the performance and commercial viability of Mg alloy anodes and contributing to the development of high-capacity,safe,and cost-effective energy storage systems.

Role of alloying and heat treatment on microstructure and mechanical properties of cast Al-Li alloys:A review

Due to the prominent advantages of low density,high elastic modulus,high specific strength and specific stiffness,cast Al-Li alloys are suitable metallic materials for manufacturing complex large-sized components and are ideal structural materials for aerospace,defense and military industries.On the basis of the microstructural characteristics of cast Al-Li alloys,exploring the role of alloying and micro-alloying can stabilize their dominant position and further expand their application scope.In this review,the development progress of cast Al-Li alloys was summarized comprehensively.According to the latest research highlights,the influence of alloying and heat treatment on the microstructure and mechanical properties was systematically analyzed.The potential methods to improve the alloy performance were concluded.In response to the practical engineering requirements of cast Al-Li alloys,the scientific challenges and future research directions were discussed and prospected.

Structure and corrosion behavior of FeCoCrNiMo high-entropy alloy coatings prepared by mechanical alloying and plasma spraying

FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy(HEA)coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and pre-pare uniform HEA coatings.Scanning electron microscopy,transmission electron microscopy,and X-ray diffractometry were employed to characterize these coatings’microstructure and phase composition.The hardness,elastic modulus,and fracture toughness of coatings were tested,and the corrosion resistance was analyzed in simulated seawater.Results show that the hardness of the coating is HV0.1606.15,the modulus of elasticity is 128.42 GPa,and the fracture toughness is 43.98 MPa·m^(1/2).The corrosion potential of the coating in 3.5wt%NaCl solution is-0.49 V,and the corrosion current density is 1.2×10^(−6)A/cm^(2).The electrochemical system comprises three parts:the electrolyte,the adsorption and metallic oxide films produced during immersion,and the FeCoNiCrMo HEA coating.Over in-creasingly long periods,the corrosion reaction rate increases first and then decreases,the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution,and the internal reaction of the coating declines.

Effect of solution treatment on the microstructure,phase transformation behavior and functional properties of NiTiNb ternary shape memory alloys fabricated via laser powder bed fusion in-situ alloying

Post-heat treatment is commonly employed to improve the microstructural homogeneity and enhance the mechanical performances of the additively manufactured metallic materials.In this work,a ternary(NiTi)91Nb9(at.%)shape memory alloy was produced by laser powder bed fusion(L-PBF)using pre-alloyed NiTi and elemental Nb powders.The effect of solution treatment on the microstructure,phase transformation behavior and mechanical/functional performances was investigated.The in-situ alloyed(NiTi)91Nb9 alloy exhibits a submicron cellular-dendritic structure surrounding the supersaturated B2-NiTi matrix.Upon high-temperature(1273 K)solution treatment,Nb-rich precipitates were precipitated from the supersaturated matrix.The fragmentation and spheroidization of the NiTi/Nb eutectics occurred during solution treatment,leading to a morphological transition from mesh-like into rod-like and sphere-like.Coarsening of theβ-Nb phases occurred with increasing holding time.The martensite transformation temperature increases after solution treatment,mainly attributed to:(i)reduced lattice distortion due to the Nb expulsion from the supersaturated B2-NiTi,and(ii)the Ti expulsion from theβ-Nb phases that lowers the ratio Ni/Ti in the B2-NiTi matrix,which resulted from the microstructure changes from non-equilibrium to equilibrium state.The thermal hysteresis of the solutionized alloys is around 145 K after 20%pre-deformation,which is comparable to the conventional NiTiNb alloys.A short-term solution treatment(i.e.at 1273 K for 30 min)enhances the ductility and strength of the as-printed specimen,with the increase of fracture stress from(613±19)MPa to(781±20)MPa and the increase of fracture strain from(7.6±0.1)%to(9.5±0.4)%.Both the as-printed and solutionized samples exhibit good tensile shape memory effects with recovery rates>90%.This work suggests that post-process heat treatment is essential to optimize the microstructure and improve the mechanical performances of the L-PBF in-situ alloyed parts.

Modified Cu active sites by alloying for efficient electrocatalytic reduction CO_(2) to CO

Transition metals like Au,Ag,and Cu have been reported to be quite active for CO_(2) 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 CO_(2) reduction reaction(CO_(2)RR).Theoretical calculations identified the combination of Ag,Cu,and Au in a face-centered cubic(fcc)alloy as an outstanding electrocatalyst for CO_(2) 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 nanoporous structured AgCuAu alloy(NP-Ag_(5)Cu_(5)Au_(5)).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 CO_(2)RR and establishes a theoretical basis for designing efficient catalysts for CO_(2) utilization.

Review of Sc microalloying effects in Al-Cu alloys

Artificially controlling the solid-state precipitation in aluminum (Al) alloys is an efficient way to achieve well-performed properties,and the microalloying strategy is the most frequently adopted method for such a purpose.In this paper,recent advances in lengthscale-dependent scandium (Sc) microalloying effects in Al-Cu model alloys are reviewed.In coarse-grained Al-Cu alloys,the Sc-aided Cu/Sc/vacancies complexes that act as heterogeneous nuclei and Sc segregation at the θ′-Al_(2)Cu/matrix interface that reduces interfacial energy contribute significantly to θ′precipitation.By grain size refinement to the fine/ultrafine-grained scale,the strongly bonded Cu/Sc/vacancies complexes inhibit Cu and vacancy diffusing toward grain boundaries,promoting the desired intragranular θ′precipitation.At nanocrystalline scale,the applied high strain producing high-density vacancies results in the formation of a large quantity of (Cu Sc,vacancy)-rich atomic complexes with high thermal stability,outstandingly improving the strength/ductility synergy and preventing the intractable low-temperature precipitation.This review recommends the use of microalloying technology to modify the precipitation behaviors toward better combined mechanical properties and thermal stability in Al alloys.

Role of micro-Ca/In alloying in tailoring the microstructural characteristics and discharge performance of dilute Mg-Bi-Sn-based alloys as anodes for Mg-air batteries

The influence of micro-Ca/In alloying on the microstructural charac teristics,electrochemical behaviors and discharge properties of extruded dilute Mg-0.5Bi-0.5Sn-based(wt.%)alloys as anodes for Mg-air batteries are evaluated.The grain size and texture intensity of the Mg-Bi-Sn-based alloys are significantly decreased after the Ca/In alloying,particularly for the In-containing alloy.Note that,in addition to nanoscale Mg_(3)Bi_(2)phase,a new microscale Mg_(2)Bi_(2)Ca phase forms in the Ca-containing alloy.The electrochemical test results demonstrate that Ca/In micro-alloying can enhance the electrochemical activity.Using In to alloy the Mg-Bi-Sn-based alloy is effective in restricting the cathodic hydrogen evolution(CHE)kinetics,leading to a low self-corrosion rate,while severe CHE occurred after Ca alloying.The micro-alloying of Ca/In to Mg-Bi-Sn-based alloy strongly deteriorates the compactness of discharge products film and mitigates the"chunk effect"(CE),hence the cell voltage,anodic efficiency as well as discharge capacity are greatly improved.The In-containing alloy exhibits outstanding discharge performance under the combined effect of the modified microstructure and discharge products,thus making it a potential anode material for primary Mg-air battery.

Simultaneously improving thermal conductivity,mechanical properties and metal fluidity through Cu alloying in Mg-Zn-based alloys

Mg-Zn-based alloys have been widely used in computer,communication,and consumer(3C)products due to excellent thermal conductivity.However,it is still a challenge to balance their mechanical performance and thermal conductivity.Here,we investigate microstructure,mechanical performance,thermal conductivity and metal fluidity of Mg-5Zn(wt.%)alloy after Cu alloying by experimental and simulation methods.First,Mg-5Zn alloy consist ofα-Mg matrix and interdendritic MgZn phases.As the Cu content increases,however,MgZn phases disappear but intragranular Mg_(2)Cu and interdendritic MgZnCu phases appear in Mg-5Zn-Cu alloys.Besides,the grain size ofα-Mg phase is refined and the volume fraction of MgZnCu phase increases as the Cu content increases.Second,Cu addition is found to improve thermal conductivity of Mg-5Zn alloy remarkably.Especially,Mg-5Zn-4Cu alloy exhibits the best thermal conductivity of 124 W/(m·K),which is mainly due to the significant reduction in both solid solubility of Zn in theα-Mg matrix and lattice distortion ofα-Mg matrix.Moreover,a stable crystal structure of MgZnCu phase also contributes to an increased thermal conductivity based on first principles and molecular dynamics simulations.Third,Cu addition simultaneously enhances strength and ductility of Mg-5Zn alloy.Tensile yield strength and elongation of Mg-5Zn-6Cu alloy reach 117 MPa and 18.0%,respectively,which is a combined result of refinement,solution,second phase,and dislocation strengthening.Finally,combined with a phase field simulation,we found that Cu addition enhances metal fluidity of Mg-5Zn alloy.On the one hand,Cu alloying not only delays dendrite growth but also prolongs solidification time.On the other hand,MgZnCu phase stabilizes the dendrite growth of theα-Mg phases by reducing energy consumption during solidification of liquid metal.This work demonstrates that Cu alloying is an ideal strategy for synergistically improving the thermal conductivity,mechanical performance and metal fluidity of Mg-based alloys.

Mitigated reaction kinetics between lithium metal anodes and electrolytes by alloying lithium metal with low-content magnesium

Lithium(Li)metal is regarded as a promising anode candidate for high-energy-density rechargeable batteries.Nevertheless,Li metal is highly reactive against electrolytes,leading to rapid decay of active Li metal reservoir.Here,alloying Li metal with low-content magnesium(Mg)is proposed to mitigate the reaction kinetics between Li metal anodes and electrolytes.Mg atoms enter the lattice of Li atoms,forming solid solution due to the low amount(5 wt%)of Mg.Mg atoms mainly concentrate near the surface of Mg-alloyed Li metal anodes.The reactivity of Mg-alloyed Li metal is mitigated kinetically,which results from the electron transfer from Li to Mg atoms due to the electronegativity difference.Based on quantitative experimental analysis,the consumption rate of active Li and electrolytes is decreased by using Mgalloyed Li metal anodes,which increases the cycle life of Li metal batteries under demanding conditions.Further,a pouch cell(1.25 Ah)with Mg-alloyed Li metal anodes delivers an energy density of 340 Wh kg^(-1)and a cycle life of 100 cycles.This work inspires the strategy of modifying Li metal anodes to kinetically mitigate the side reactions with electrolytes.

热处理对Cu-Ni-Cr-Si合金性能提升的机理研究

为了深入了解Cu-Ni-Cr-Si系列合金的综合性能,对比分析了Cu-Ni-Cr-Si合金热处理前后合金的显微硬度、拉伸性能以及显微组织等的变化规律。研究发现,热处理后的Cu-Ni-Cr-Si合金的拉伸性能明显提升,显微硬度也呈现出相同的变化趋势。Cu-Ni-Cr-Si合金是典型的沉淀时效强化合金,热处理过程中溶质原子扩散,从而形成析出相,细小、弥散的析出相分布在合金的晶界中会阻碍位错运动,从而提高了合金的力学性能。显微组织研究发现,热处理后晶粒的尺寸显著变大,与此同时热驱动力促使析出相生成,一般为Ni/Si相和Cr/Si相,析出相具有较高的硬度,合金的显微硬度在热处理之后也会有显著提升。电子背散射衍射(EBSD)分析发现,热处理之后小角度晶界转变为大角度晶界,局域取向差降低,推断位错密度降低。除此之外,溶质原子Cr、Ni、Si从基体中析出,对基体具有一定的净化作用,导电率由29.665%IACS提高到35.124%IACS。

Cr含量对Fe-Cr-Si三元系合金组织和耐蚀性能的影响

为了探究Cr元素含量对Fe-Cr-Si三元系合金组织和耐蚀性能的影响,采用SEM、XRD等仪器对3种不同Cr含量的Fe-Cr-Si系合金的显微组织、硬度及其腐蚀行为展开研究,系统分析了Cr含量变化对Fe-Cr-Si系合金材料的显微组织、硬度及耐蚀性能的影响。结果表明:3种不同Cr含量的Fe-Cr-Si合金均由树枝晶和枝晶间基体组成。随着Cr含量的增加,枝晶间Fe3Si相增多,Fe-Cr固溶体相生成。相比Fe8Cr10Si合金,Fe16Cr10Si合金的硬度降低16%。10%(质量分数)HCl溶液浸泡腐蚀试验结果表明,Cr含量较低的Fe8Cr10Si合金的腐蚀情况最为严重,出现较深的腐蚀坑,腐蚀坑中的片状硅化物未能有效地防止合金被侵蚀。固溶态Cr含量的升高是促使Fe-Cr-Si合金耐蚀性能提升的主要原因。

Si含量对Fe-Cr-Si合金高温耐磨性能的影响

为研究Si含量对Fe-Cr-Si合金高温耐磨性能的影响,改善Fe-Cr-Si合金在高温环境下的耐磨性能,采用真空电弧熔炼制备了4种不同Si含量(原子分数5%、10%、15%、20%)的Fe-Cr-Si合金,研究了Si含量变化对其高温耐磨性能的影响。结果表明,4种Fe-Cr-Si合金均由单相组织构成,Si含量的增加使得合金硬度逐渐升高,并且促进了金属硅化物Fe_(3)Si的形成。随着Si含量的增加,Fe-Cr-Si合金的摩擦系数和磨损率逐渐减小,磨损机制由剥落磨损转变为氧化磨损、磨粒磨损和黏着磨损。

基于局部离群因子与隔离森林的激光超声缺陷检测

针对激光超声(LU)缺陷检测中最大振幅图存在伪像的问题,结合主成分分析(PCA)和两种无监督的机器学习算法局部离群因子(LOF)与隔离森林(IF),以实现对LU数据的无监督异常检测。首先,利用PCA算法对LU数据进行降维处理,减轻了LU数据的复杂度;其次,利用LOF算法和IF算法进行了数据异常值的识别分析,并利用累积分布函数和核密度估计确定异常值的阈值大小;最后,对比了LOF算法、IF算法以及最大振幅图的检测结果。结果表明:LOF算法有更优的缺陷识别精度和更低的误判率。

Cr-Si合金钢表面纳米层对低温离子渗硫的影响

利用超音速微粒轰击技术在调质处理的Cr-Si合金钢表面制备了厚度约25μm的纳米晶层。透射电镜（TEM）对表面结构的观察表明,最表面层形成了具有随机取向等轴的纳米晶粒,晶粒的平均尺寸约为16nm。对表面纳米化试样进行低温离子渗硫处理,在纳米结构表层形成了厚度约10μm的硫化物固体润滑薄膜。对硫化物层的结构分析结果表明,试样经表面纳米化处理后表面的扩渗性能和化学反应能力明显提高,在硫化物层和基体的界面处出现了厚度约为1-2μm的硫元素的扩渗层。表面纳米化试样表面硫化物的含量明显高于原始试样的硫化物的含量,且硫化物层主要由FeS相所构成,而在原始试样的硫化物层中FeS2的含量相对较高。表面层的晶界体积分数以及原子活性提高是表面纳米化试样表面化学反应能力和扩渗能力提高的主要原因。

基于热处理工艺的拖拉机发动机铝合金组织性能研究

采用不同时长的热处理工艺,对拖拉机发动机铝合金组织性能进行了对比分析。结果表明:热处理后,铝合金性能得到了较大程度的提高,若优先考虑材料性能,则应该采用180℃×4 h的单级热处理时效;若优先考虑工艺效率和成本,则可以采用150℃×1 h+170℃×1 h的双级热处理时效。

Cr-Si合金钢表面纳米晶热稳定性的研究

采用超音速微粒轰击技术在Cr-Si合金钢的表面制备了纳米结构层。最表面层的晶粒尺寸约为16nm。利用X射线衍射(XRD)技术和透射电镜(TEM)分析技术对退火后表面纳米晶的结构变化进行分析。结果显示:当温度低于450℃进行退火时,表面纳米晶的尺寸变化不大。当退火温度达到450℃时,表面纳米晶失去稳定急剧长大到100nm左右。分析表明在低于450℃时,Cr-Si合金钢表面纳米晶具有良好的热稳定性,表面纳米晶的本征结构、退火时结构的动态回复以及渗碳体颗粒对晶界运动的阻碍是决定其具有一定的热稳定性的主要因素。

Effects of alloying and deformation on microstructures and properties of Cu-Mg-Te-Y alloys

New copper alloys with high mechanical properties and high electrical conductivity were prepared, and the effects of addition of minor Mg and Y elements on microstructures and properties were studied. The high tensile strength of above 510 MPa, high elongation of 11%and high electrical conductivity of over 63%IACS can be simultaneously obtained in Cu-0.47Mg-0.20Te-0.04Y alloy after deforming and annealing treatment. Effects of purification together with the grain refining by Y and solid-solution strengthening by Mg are appropriate for enhancing mechanical properties and electrical conductivity of the copper alloys.

Effect of surface diffusion alloying on erosion wear property of ZM5 magnesium alloy

Specimens of ZM5 magnesium alloy were dipped into the mixed powder of Al and Zn at （390±5） ℃ for 8 h in argon gas protective environment and subjected to surface diffusion alloying processing （SDAP）. The erosion wear behaviors of ZM5 magnesium alloy before and after SDAP were investigated in two different erosion wear environments： oil and quartz environment; tap water and quartz environment. The surfaces of erosion wear specimens exhibited cutting scratch grooves in the oil and quartz environment. Corrosive attack was weak and cutting wear mechanism was responsible for the mass loss. When the erosion wear medium was changed to tap water and quartz environment, corrosion pits and cracks were obviously observed after erosion wear test. The corrosion from tap water and the scour from quartz intensified mass losses. Compared with the untreated specimens, the application of SDAP improved the erosion wear resistance in the same environment.