等离子熔覆制备高熵合金涂层耐腐蚀性能的研究进展

高熵合金涂层具有易于制备、结构简单和综合性能优良等特点,成为高熵合金领域的研究热点.为探究等离子熔覆制备高熵合金涂层的腐蚀行为,本文阐述了近年有关高熵合金涂层典型制备方法、特点及利用等离子熔覆制备高熵合金涂层的优势.总结了等离子熔覆制备高熵合金涂层耐腐蚀性能的国内外研究进展.重点综述了高熵合金涂层的微观组织、相组成和合...     

合金元素对激光熔覆高熵合金涂层影响的研究进展

介绍了激光熔覆高熵合金涂层的硬度、耐蚀性、热稳定性及抗高温氧化性等性能。总结了合金元素对高熵合金涂层性能的影响。阐述了激光熔覆技术制备高熵合金涂层近些年的研究进展,并且指出了该技术制备涂层所存在的问题以及未来展望,以期制备出性能优异的高熵合金涂层。     

高熵合金涂层的研究进展

高熵合金涂层表现出比传统涂层更优良的综合性能,具有深入的研究价值。概述了近年来有关高熵合金涂层的研究进展,首先总结了高熵合金涂层的制备工艺(磁控溅射技术、热喷涂技术和激光熔覆技术等),分析了各制备工艺的优缺点,而后进一步分析研究者们如何通过元素、微观结构和制备工艺等方面优化高熵合金涂层性能。此外,就高熵合金涂层在工业上的应用前景和研究方向进行展望。     

高熵合金制备工艺的研究进展

对高熵合金的成分、结构、制备工艺和性能等方面进行了总结,综述了国内外的研究进展,讨论了高熵合金的研究和发展趋势。     

高熵非晶材料及其增材制造技术研究进展

高熵非晶合金具有独特的物理、化学和力学性能以及更好的热稳定性,因而其制备技术成为国内外重要的研究热点之一. 然而利用传统技术制备高熵非晶材料时会产生晶粒粗大及材料浪费等缺点,难以满足工艺生产需要. 而增材制造技术的精准制造和快速冷却等特点可以解决这一问题,制备出各项性能优越的高熵非晶合金. 简要介绍了高熵非晶材料的研究体系和常用制造方法,着重阐述了高熵非晶材料的断裂强度、耐腐蚀性和热稳定性的研究,对增材制造技术的工艺特征和优势,以及利用增材制造技术制备高熵非晶合金的科学难点作出了总结. 结果表明,利用增材制造技术有利于获得致密均匀的高熵非晶材料,但对于非晶相形成的解释仅限于高熵合金4大效应.最后阐述了近年来利用常用的两种增材制造手段制造高熵非晶合金的研究,并对增材制造技术制备高熵非晶材料的发展趋势提出了展望.     

磁控溅射制备高熵合金薄膜研究进展∗

作为新兴合金材料,多主元高熵合金打破了传统合金中主要组成元素为一种或两种的合金设计理念,由至少五种主要元素构成,从而获得的高熵效应使其在性能上往往比传统合金具有更大的优势,如高硬度、高强度、抗高温氧化、耐腐蚀等。 近年来,高熵合金薄膜的性能及制备技术同样备受学术界和工业界的关注。 磁控溅射薄膜制备技术具有成膜温度低、膜层致密、结合力好等优点,已逐渐应用于高熵合金薄膜的制备及性能研究,具有非常大的工程应用前景。 介绍直流、射频、离子束及脉冲磁控溅射的特点及其在高熵合金薄膜中的应用,重点分析不同磁控溅射技术下制备的高熵合金薄膜的相结构特点和规律,并系统地阐述薄膜优异的各种性能,最后展望磁控溅射技术制备高熵合金薄膜发展的方向。     

高熵合金涂层制备工艺的研究现状

高熵合金涂层凭借其独特的设计理念,具有优于传统合金涂层的优异力学性能和物理化学性能,在多个领域的应用潜力较强,引起了研究者的广泛关注。本文主要综述了现阶段高熵合金涂层的主要制备工艺,激光熔覆技术、热喷涂技术、冷喷涂技术、磁控溅射技术、电化学沉积技术等的最新研究进展,详细分析了每种制备工艺的优缺点及其制备的高熵合金涂层的性能特点,并提出了现阶段高熵合金涂层研究过程中存在的问题,为后续高熵合金涂层的研究、应用及发展提供参考及指导。     

机械合金化制备高熵合金研究进展

高熵合金作为一种新型合金逐渐被人们所关注,机械合金化是一种制备先进材料的固态加工工艺,利用机械合金化制备高熵合金也为高熵合金的发展及应用开拓了广阔的领域。本文介绍了高熵合金的简单概念,并从机械合金化中的元素选择、高熵合金粉末的后处理工艺及机械合金化制备高熵合金的研究方向三个方面综述了其研究进展。     

激光熔化沉积CrMnFeCoNi高熵合金组织和低温力学性能

采用激光熔化沉积和铸造技术分别制备了CrMnFeCoNi高熵合金。通过X射线衍射(XRD)、金相腐蚀、扫描电镜(SEM)和力学拉伸实验等分析手段对不同方法制备的CrMnFeCoNi高熵合金相组成、微观组织及力学性能进行了对比研究。结果表明:通过激光熔化沉积和铸造技术制备的CrMnFeCoNi高熵合金均为面心立方(FCC)单相固溶体结构;采用激光熔化沉积技术制备的CrMnFeCoNi高熵合金具有更为均匀的元素分布;随着温度从293 K降低到77 K,激光熔化沉积技术制备的CrMnFeCoNi高熵合金的拉伸强度与塑性分别从518 MPa、55%提升到878 MPa、95%,表现出优异的低温力学性能。     

轻质高熵合金的研究进展

高熵合金是由多种元素以等摩尔或近等摩尔的比例混合形成的一种新型合金,较大的密度极大地限制了其应用。为了降低高熵合金的密度,出现了由Al、Li、Mg、Ti等轻质合金元素组成的轻质高熵合金,其在交通运输、航空航天领域潜在的应用前景引起了广泛关注。本文阐述了轻质高熵合金的研究现状,分析了轻质高熵合金的组元设计方法、相组成以及制备工艺,进而归纳总结了目前不同种类的轻质高熵合金的性能,包括高强度、高硬度、高温抗氧化性、耐蚀性能等。最后总结了轻质高熵合金目前存在的一些问题以及对轻质高熵合金未来的研究方向进行了展望。     

轻质高熵合金的研究进展与展望

高熵合金是一种具有优异物理化学性能的新型合金,其中含有轻质元素的轻质高熵合金具有较高的比强度和比硬度及耐蚀性能等突出特点,其潜在的工程应用价值引起了人们的关注。因此,本文详细阐述了轻质高熵合金的研究现状,归纳了轻质高熵合金的组元设计规则与方法,分析了轻质高熵合金的微观相结构,总结了高熵合金的各种性能,探讨了轻质高熵合金目前存在的问题,并提出了轻质高熵合金的发展趋势。     

A Novel CoFe2NiMn0.3AlCux High-Entropy Alloy with Excellent Magnetic Properties and Good Mechanical Properties

In the present study,we investigate the crystal structure of high-entropy alloys (HEAs) in the form of CoFe2NiMn0.3AlCux(x =0.25,0.50,0.75,and 1.00) and their mechanical and magnetic properties.The CoFe2NiMn0.3AlCux alloys are composed of a mixture of a body-centered cubic (BCC) and a face-centered cubic (FCC) solid solution.The increased amounts of cop-per (Cu) boost both alloy strength and plastic ductility.The CoFe2NiMn0.3AlCu1.0 HEAs demonstrate excellent mechanical properties,such as a high strength of 1832 MPa and a large plastic ductility of 22.38％.Magnetic property measurements on this alloy system indicated high saturated magnetization and high coercivity.The coercivity of the tested alloys lies in the range between 40 and 182 Oe,suggesting that the alloys have semi-hard magnetic properties.This study suggests that the present CoFe2NiMn0.3AlCux HEAs could serve as potential candidates for soft magnets in electromagnetic applications.     

Microstructure,Mechanical Properties,and Corrosion Behavior of MoNbFeCrV,MoNbFeCrTi, and MoNbFeVTi High-Entropy Alloys

The development of high-entropy alloys(HEAs) has stimulated an ever-increasing interest from both academia and industries.In this work, three novel MoNbFeCrV, MoNbFeCrTi, and MoNbFeVTi HEAs containing low thermal neutron absorption cross section elements were prepared by vacuum arc melting. The microstructure, mechanical properties, and corrosion behaviors were investigated. A dominant body-centered cubic(BCC) phase was present in all these three HEAs. In addition,an ordered Laves phase was found to be another major phase in both MoNbFeCrV and MoNbFeCrTi alloys, whereas an ordered BCC(B2) phase was observed in the MoNbFeVTi alloy. The phase formation in these three alloys was discussed. It is found that the formation of the secondary phase in these alloys is mainly ascribed to the large atomic size difference and electronegativity difference. All the three HEAs show high hardness, high yield strength but limited plasticity. Moreover, the MoNbFeCrV, MoNbFeCrTi and MoNbFeVTi alloys exhibit excellent corrosion resistance in both deaerated 1 mol/L NaCl and 0.5 mol/L H _2 SO _4 solutions at room temperature. However, further composition adjustment and/or thermomechanical processing is required to enhance the mechanical properties of the three alloys.     

Development and Property Tuning of Refractory High-Entropy Alloys: A Review

In the past decade, multi-principal element high-entropy alloys (referred to as high-entropy alloys, HEAs) are an emerging alloy material, which has been developed rapidly and has become a research hotspot in the fi eld of metal materials. It breaks the alloy design concept of one or two principal elements in traditional alloys. It is composed of fi ve or more principal elements, and the atomic percentage (at.%) of each element is greater than 5%but not more than 35%. The high-entropy eff ect ca...     

Empirical design of single phase high-entropy alloys with high hardness

We collect the available basic properties of nearly 100 high-entropy alloys (HEAs) with a single face centered cubic (fcc) or body centered cubic (bcc) phase. HEAs crystallizing in the fcc structure are mainly composed of the late 3d elements (LTM-HEAs), whereas HEAs consisting of the early (refractory) transition elements and the LTM-HEAs containing an increased level of bcc stabilizer form the bcc structure. Guided by the solid solution theory, we investigate the structure and hardness of HEAs as a function of the valence electron concentration (VEC) and the atomic size difference (δ). The fcc structure is found for VEC between 7.80 and 9.50, whereas the structure is bcc for VEC between 4.33 and 7.55. High strength is obtained for an average valence electron number VEC ∼ 6.80 and for an average atomic size difference δ ≈ 6%. Based on these empirical correlations, one can design the high-entropy alloys with desired hardness.     

Role of Various Parameters in the Formation of the Physicomechanical Properties of High-Entropy Alloys with BCC Lattices

An analysis of simple structures of the solid-solution non-ordered high-entropy alloys (HEAs) with a bcc crystal lattice has allowed us to determine the effect of various parameters on their physicomechanical properties. It was found that, as the hardness increases, the size mismatch results in a decrease in the modulus of elasticity; however, the normalized hardness characteristic increases. It has been found that, when the enthalpy of mixing of the bcc high-entropy alloys shifts to negative values, its effect on the hardness and modulus of elasticity is nonmonotonic. A formula for calculating the modulus of elasticity of high-entropy alloys with a bcc structure has been suggested that is based on the alloy composition and role of the most refractory metallic component.     

The high-entropy alloys with high hardness and soft magnetic property prepared by mechanical alloying and high-pressure sintering

The equiatomic multiprincipal CoCrFeCuNi and CoCrFeMnNi high-entropy alloys (HEAs) were consolidated via high pressure sintering (HPS) from the powders prepared by the mechanical alloying method (MA). The structures of the MA'ed CoCrFeCuNi and CoCrFeMnNi powders consisted of a face-centered-cubic (FCC) phase and a minority body-centered cubic (BCC) phase. After being consolidated by HPS at 5 GPa, the structure of both HEAs transformed to a single FCC phase. The grain sizes of the HPS'ed CoCrFeCuNi and CoCrFeMnNi HEAs were about 100 nm. The alloys keep the FCC structure until the pressure reaches 31 GPa. The hardness of the HPS'ed CoCrFeCuNi and CoCrFeMnNi HEAs were 494 Hv and 587 Hv, respectively, much higher than their counterparts prepared by casting. Both alloys show typical paramagnetism, however, possessing different saturated magnetization. The mechanisms responsible for the observed influence of Cu and Mn on mechanical behavior and magnetic property of the HEAs are discussed in detail.     

Alloy Design and Properties Optimization of High-Entropy Alloys

This article reviews the recent work on the high-entropy alloys (HEAs) in our group and others. HEAs usually contain five or more elements, and thus, the phase diagram of HEAs is often not available to be used to design the alloys. We have proposed that the parameters of ?? and ?? can be used to predict the phase formation of HEAs, namely ??????1.1 and ??????6.6%, which are required to form solid-solution phases. To test this criterion, alloys of TiZrNbMoV _x and CoCrFeNiAlNb _x were prepared. Their microstructures mainly consist of simple body-centered cubic solid solutions at low Nb contents. TiZrNbMoV _x alloys possess excellent mechanical properties. Bridgman solidification was also used to control the microstructure of the CoCrFeNiAl alloy, and its plasticity was improved to be about 30%. To our surprise, the CoCrFeNiAl HEAs exhibit no apparent ductile-to-brittle transition even when the temperatures are lowered from 298?K to 77?K.     

难熔高熵合金在反应堆结构材料领域的机遇与挑战

传统反应堆结构材料性能已趋于极限,亟需开发新型材料。难熔高熵合金是以多种难熔元素作为主元的新型金属材料,具有独特的力学、物理和化学性质,尤其在高温力学、抗辐照等方面表现出优异的性能。难熔高熵合金在第4代核裂变反应堆包壳材料、核聚变堆面向第一壁材料等关键领域具有广阔的应用前景。本文结合具有代表性的文献,围绕难熔高熵合金的力学性能、抗辐照性能、抗氧化性能阐述了其强化机制与抗辐照机理,梳理了难熔高熵合金的发展脉络,在此基础上展望了难熔高熵合金在反应堆结构材料领域的应用前景。     

Phase Stability of Low-Density,Multiprincipal Component Alloys Containing Aluminum,Magnesium, and Lithium

A series of low-density, multiprincipal component alloys containing high concentrations of Al, Mg, Li, Zn, Cu and/or Sn was designed using a strategy based on high-entropy alloys (HEAs). The alloys were prepared by induction melting under high-purity argon atmosphere, and the resulting microstructures were characterized in the as-cast condition. The resulting microstructures are multiphase and complex and contain significant volume fractions of disordered solutions and intermetallic compounds. By analyzing the atomic size difference, enthalpy of mixing, entropy of mixing, electronegativity difference, and valence electron concentration among the constituent elements, modified phase formation rules are developed for low-density multiprincipal component alloys that are more restrictive than previously established limits based on more frequently studied HEAs comprising mostly transition metals. It is concluded that disordered solid solution phases are generally less stable than competing ordered compounds when formulated from low-density elements including Al, Mg, and Li.