Microstructure and corrosion resistance of Fe-Al intermetallic coating on 45 steel synthesized by double glow plasma surface alloying technology

A binary Fe-Al alloyed layer was synthesized on 45 steel by means of double glow plasma surface alloying technique. The corrosion-resisting layer prepared is composed of a sedimentary layer and a diffusion layer, with a total thickness of about 180 μm. The aluminum content of the alloyed layer shows gradual change from surface to the inside of substrate. The ideal profile is beneficial to the metallurgical bonding of the surface alloying layer with substrate materials. The microstructure of both layers consists of the Fe-Al intermetallic compound, which is FeAl with B2 structure in the sedimentary layer and Fe3Al with incompletely ordered DO3 structure in the diffusion layer. The protective film exhibits high micro-hardness. In comparison with the substrate of 45 steel, the corrosion resistance of the aluminized sample is much higher in 2.0% Na2S and 0.05 mol/L Na2SO4 + 0.5 mol/L NaCl mixed solutions.

Fe-Al金属间化合物的第一性原理研究综述

Fe-Al金属间化合物具有密度低、比强度高、抗高温氧化和耐腐蚀性良好等优点,且成本低廉,成为镍基高温合金潜在的替代结构材料。综述了利用第一性原理计算研究元素掺杂/微合金化对Fe-Al金属间化合物及涂层的室温脆性、高温强度、界面结合、抗高温氧化及耐腐蚀性能影响的研究进展,设计了第一性原理研究B2型Fe-Al合金耐氯化盐腐蚀机理的理论计算方案,展望了第一性原理计算应用于Fe-Al合金及涂层材料研究的发展方向。

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.

扫描速度对激光熔覆Fe-Al合金熔覆层组织及性能的影响

为提高工程用高强钢的耐蚀性并降低使用材料成本,采用光纤激光器在Q960E高强钢表面以同轴送粉工艺制备Fe-Al合金熔覆层,研究不同扫描速度对组织及耐蚀性的影响.结果表明,熔覆层的晶粒形态与元素分布及含量都受到扫描速度的影响.物相主要由DO3结构的Fe3Al相和B2结构的FeAl相以共晶形式组成.熔覆层的硬度随扫描速度增加受晶粒细化的影响逐渐提高.3种扫描速度下的熔覆层自腐蚀电位随扫描速度增加先上升后下降,自腐蚀电流密度先减小后增大,经过极化后的熔覆层表面点蚀坑随扫描速度的增加先由深变浅,后点蚀坑面积扩大.

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.

低剩磁高Al含量Fe-Al合金的制备及性能研究

低剩磁高Al含量的Fe-Al合金是一类非常重要的金属结构材料,在工业生产中有着重要的用途。现代工业经济的飞速发展,使得对低剩磁高Al含量的Fe-Al合金制备技术和性能的深入研究变得更加重要。作者就低剩磁高Al含量Fe-Al合金的制备技术和性能进行了深入的分析与研究。研究结果表明制取的低剩磁高Al含量Fe-Al合金材料性能优良,可以替代现在使用的晶粒取向Si-Fe合金。

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.

Synthesis and grain growth kinetics of in-situ FeAl matrix nanocomposites(Ⅰ):Mechanical alloying of Fe-Al-Ti-B composite powder

Three nanocrystalline alloys, Fe50Al50, Fe42.5Al42.5Ti5B10 and Fe35Al35Ti10B20 (molar fraction, %), were synthesized from elemental powders by high-energy ball milling. The structural evolutions and morphological changes of the milled powders were characterized by X-ray diffractometry(XRD), transmission electron microscopy(TEM) and scanning electron microscopy(SEM). The effects of different Ti, B additions on the structure and phase transformation in these alloys were also discussed. It is observed that the diffusion of Al, Ti, B atoms into Fe lattice occurs during milling, leading to the formation of a BCC phase identified as Fe(Al) or Fe(Al, Ti, B) supersaturated solid solution. Fe-based solid solution with nanocrystalline structure is observed to be present as the only phase in all the alloy compositions after milling. Furthermore, the contents of Ti, B affect the formation of mechanical alloying products, changes in the lattice parameter as well as the grain size.

Fe-Al、Ti-Al和Ni-Al系金属间化合物多孔材料的研究进展

总结Fe-Al、Ti-Al、Ni-Al 3大系金属间化合物的物相结构和基本特性,论述Fe-Al、Ti-Al和Ni-Al 3大类金属间化合物多孔材料的制备方法、孔结构表征以及耐腐蚀性能,并指出孔结构参数的可控性研究、复合材料的制备和焊接性能的提高是金属间化合物多孔材料未来的研究重点。

Ni-Al系、Fe-Al系和Ti_3Al金属间化合物研究进展

简要介绍了金属间化合物的熔炼与铸造工艺。论述了Ni Al系 (包括NiAl和Ni3 Al)、Fe Al系 (包括Fe3 Al和FeAl)及Ti3 Al基金属间化合物高温结构材料的研究现状和发展动态 ,分析了上述合金存在的问题及解决办法 ,介绍了它们在不同领域的潜在应用。

Fe-Al合金多孔材料研究进展

Fe-Al合金多孔材料具有比常规多孔材料更好的耐高温氧化、耐腐蚀、高强度等优异性能,但是由于室温脆性大、延展性低,阻碍了其进一步发展。本文综述了Fe-Al合金多孔材料的特性、应用现状以及在制备和应用中存在的问题。通过阐述多孔材料在洁净煤技术的应用现状,分析了Fe-Al合金多孔材料的研究方向和发展趋势。

Fe-Al金属间化合物基复合材料的研究进展

对Fe Al金属间化合物基复合材料及相关领域的研究现状进行了综合评述。着重介绍了增强相与基体界面的相容性、连续纤维及颗粒增强Fe Al金属间化合物基复合材料的制备工艺和弥散强化Fe Al金属间化合物基纳米复合材料的合成与烧结,以及Fe Al金属间化合物基复合材料的力学性能等方面取得的研究成果。并就目前研究的不足以及该研究领域的发展方向提出了一些看法。