激光熔覆高熵合金涂层组织结构及强化机理研究进展

激光熔覆作为一种绿色、高效的表面处理技术，能够快速制备组织致密、晶粒细小，与基体呈高强度冶金 结合的涂层，是近年来高熵合金领域的研究热点之一。概述了现有高熵合金涂层材料体系和制备方法，重点讨论 了激光熔覆CoCrFeNi-M 典型过渡族高熵合金涂层的组织结构，及其耐磨、耐蚀、抗高温氧化等性能，并归纳了 涂层的强化机制和方法。CoCrFeNi-M 系合金涂层主要呈现FCC 固溶体结构，综合力学性能普遍较好，通过合金 体系调控，在细晶强化、固溶强化、第二相强化等作用下，能够获得硬度、耐磨性、耐蚀性等性能的进一步提升。 同时，概述了激光熔覆难熔高熵合金涂层的组织结构，耐磨、耐蚀、抗高温氧化性能及性能强化机制，该体系合 金涂层主要呈现BCC 固溶体结构，硬度较高但室温韧性普遍不足，具有较好的高温强度，在高温领域具有较好 的应用前景，但抗高温氧化性能普遍不足，仍需通过合金体系优化进一步提升。此外，总结了基于激光熔覆技术 开展的高熵合金涂层制备及研究中存在的问题和不足，并展望了未来的发展方向。     

钨铜复合材料的研究及应用现状

钨铜复合材料作为一种重要的粉末冶金材料,具有优异的性能,是制造电触头和电极、焊接和电锻模、散热片、封装材料等的理想材料,广泛应用于电气、电子、航空航天和军事等工业领域中。近年来,随着先进制备工艺的研究和发展,钨铜复合材料的性能不断提升,本文主要描述了钨铜复合材料的制备方法、性能改进以及应用现状等。     

铁基粉末冶金烧结材料的疲劳与失效行为研究进展

铁基粉末冶金结构零件以其独特的优点和巨大的竞争力已在汽车等行业获得广泛的应用.材料疲劳性能的研究目前仍然是应用和科学研究中的一个重要领域.综述了近年来国内外铁基粉末冶金材料的疲劳与失效行为的研究成果,包括成分、组织和制备工艺等因素对铁基粉末冶金材料的疲劳性能、疲劳裂纹萌生与扩展机制的影响,以及铁基粉末冶金材料的疲劳裂纹扩展速率等方面的研究成果.指出了加强国内相关领域研究,有利于促进粉末冶金学科发展和提升国内的粉末冶金技术水平,对拓展铁基粉末冶金零件的应用具有重要的现实意义.     

从PM2004看世界粉末冶金的发展现状

详细介绍了2004年粉末冶金世界大会的基本情况, 概述了国际粉末冶金工业现状, 并按照类别阐述了粉末冶金各技术领域以及材料产品, 如粉末烧结钢、粉末注射成形、粉末制备技术、粉末压制技术、粉末烧结理论与技术、粉末多孔材料、硬质合金、粉末轻金属、粉末零件后续处理加工技术、粉末冶金过程模拟与标准化以及粉末功能材料等的发展趋势。世界粉末冶金的发展现状和趋势表明粉末冶金技术是工业化集成技术, 而不仅仅是一种高技术。     

粉末冶金工模具钢的生产技术及应用研究进展（上）

工模具钢是一种具有高强度、硬度、耐磨性和耐热性的特殊钢材,广泛应用于金属加工、注塑及压铸模具、汽车制造等行业。传统熔铸方法制备的工模具钢易出现成分偏析及粗大碳化物,且难以通过锻造等加工方法消除,导致材料性能变差。粉末冶金工模具钢的组织均匀、碳化物弥散细小、合金成分含量高,可实现复杂形状和结构的制造,其工模具产品具有高性能、高精度、长寿命等优势,在高端制造业领域有重要的应用前景。因此,对粉末冶金工模具钢的发展历史,生产技术及其应用进行了综述,介绍了工模具钢粉末工业化制备的技术革新,分析了粉末冶金工模具钢的制备方法及组织性能特点,最后归纳了粉末冶金工模具钢的分类及应用,并对其未来的发展趋势进行了展望。     

高熵稀土盐类热障/环境障陶瓷涂层体系研究进展

高熵陶瓷是近年来新型陶瓷研究领域的一大热点，在航空工业领域有着巨大的发展和应用前景。基于高熵策略设计的高熵氧化物陶瓷涂层可以较好地解决当前热障/环境障涂层在高温下服役寿命、抗氧化性、抗CMAS(钙镁铝硅氧化物)腐蚀等关键性能不足的问题。综述了近几年不同体系的五元高熵稀土盐类材料在热障/环境障涂层领域作为候补材料的研究进展，总结了该类材料在结构、性能及主要应用领域方面的特点。最后展望了高熵稀土盐类陶瓷涂层的发展方向，为新材料体系的进一步研发和关键性能优化提供思路。     

粉末冶金钛合金制备技术与研究

钛合金是一种性能优良的金属，在许多领域都得到了应用。但由于钛合金制备材料的提取难度较大，机加工不易，生产成本一直较高。因此，降低钛合金制备成本的粉末冶金技术至关重要。基于此，以粉末冶金钛合金生产制备过程为基础，结合国内市场对其需求和发展方向，重点分析了其在当前的应用情况，以期为钛合金的工业生产提供一定的参考。     

高氮不锈钢粉末冶金制备技术的研究进展

高氮不锈钢作为一种重要新型工程材料,具有优异的力学性能和耐腐蚀性能,受到国内外广泛重视。介绍了粉末冶金制备高氮不锈钢的原理和特点;论述了高氮不锈钢粉末的制备与成形技术;指出了利用粉末冶金制备高氮不锈钢所具有的技术优势,其中注射成形——氮化烧结工艺更具发展潜力。     

高氮不锈钢粉末冶金制备技术的研究进展

高氮不锈钢作为一种重要新型工程材料,具有优异的力学性能和耐腐蚀性能,受到国内外广泛重视。介绍了粉末冶金制备高氮不锈钢的原理和特点;论述了高氮不锈钢粉末的制备与成形技术;指出了利用粉末冶金制备高氮不锈钢所具有的技术优势,其中注射成形——氮化烧结工艺更具发展潜力。     

难熔高熵合金激光增材制造：研究进展与展望

难熔高熵合金（RHEAs）是一类以Nb, Mo, W, Ta等难熔元素为主元的高熵合金（HEAs），具有简单的相结构和优异的高温综合力学性能，在航空航天、核能和石油等领域具有广阔的应用前景。由于RHEAs室温脆性难加工的特点，传统的工艺方法在制备RHEAs时存在制造过程复杂、周期长、材料利用率低、成本高等诸多问题，极大地限制了RHEAs的发展和应用。激光增材制造（LAM）技术因其能实现复杂零件的直接自由成形，而逐渐成为制备RHEAs的一条重要途径，为RHEAs的研发和应用带来了新的契机。对近年来激光增材制造RHEAs的研究现状进行了综述，介绍了激光增材制造RHEAs的成形特性，分析了RHEAs打印件的相组成和显微组织特征，总结了打印件的显微硬度、压缩强度以及耐磨、耐腐蚀和抗高温氧化性能。最后归纳出目前激光增材制造RHEAs的现存问题，并对其未来的发展趋势进行了展望。     

Powder metallurgy and high-entropy alloys: update on new opportunities

ABSTRACT

This article addresses the development of high-entropy alloys (HEAs) fabricated via Powder Metallurgy (PM) techniques. There are potential opportunities for PM techniques to produce ‘different’ HEAs and offer alternative routes to obtain special compositions. The potential for PM is vast, and the obtained properties are highly competitive with those from HEAs produced by ingot casting. Considerable work must still be done to provide the market with reasons to use PM instead of other processing routes. Since article [Torralba JM, Alvaredo P, García-Junceda A. High-entropy alloys fabricated via powder metallurgy. A critical review. Powder Metall. 2019;62(2), doi:10.1080/00325899.2019.1584454] was published in 2019, more than 100 research works have been issued on this topic. The objective of this paper is to provide an update on some of the new opportunities that have been proposed in the last months.     

激光增材制造技术制备高熵合金研究进展

介绍了激光增材制造高熵合金的工艺方法,从成形工艺、合金元素含量（摩尔分数）、热处理工艺和增强相添加等几个方面综述了国内外激光增材制造高熵合金的研究进展,分析了激光熔化沉积和选区激光熔化成形两种主要激光增材制造技术,以及两种技术制备高熵合金的微观结构和力学性能,指出了高熵合金激光增材制造技术的发展趋势及存在的主要问题,并提出了改进措施。     

Research on Bulk-metallic Glasses and High-entropy Alloys in Peter K. Liaw’s Group and with His Colleagues

Bulk-metallic glasses (BMGs) and high-entropy alloys (HEAs) have attracted extensive attention in the field of metallic materials research for several decades due to their extraordinary properties. Many scientists and researchers have significantly contributed to developing new classes of metallic alloys, such as BMGs and HEAs, for various applications. Liaw’s group and his colleagues have focused on the fundamental understanding of unique features, structures, and properties in BMGs and HEAs as well as the development of new types of metallic materials. In this article, we summarized the research work of Liaw’s group and his colleagues by reviewing relevant papers. The goal is to provide an understanding of the current research progression in BMGs and HEAs while further encouraging young and junior researchers to be involved in the field of structural materials research pertaining to these classes of exotic alloy systems.

     

Effect of Wear Debris Entrapment on the Tribological Performance of AlCoCrFeNi Produced by Selective Laser Melting or Spark Plasma Sintering

Metallurgical and Materials Transactions A - This study aimed to investigate the microstructure and tribological properties of the equiatomic AlCoCrFeNi high-entropy alloys (HEAs) fabricated using...     

High-entropy alloys fabricated via powder metallurgy. A critical review

High-entropy alloys (HEAs) have attracted a great deal of interest over the last 14 years. One reason for this level of interest is related to these alloys breaking the alloying principles that have been applied for many centuries. Thus, HEAs usually possess a single phase (contrary to expectations according to the composition of the alloy) and exhibit a high level of performance in different properties related to many developing areas in industry. Despite this significant interest, most HEAs have been developed via ingot metallurgy. More recently, powder metallurgy (PM) has appeared as an interesting alternative for further developing this family of alloys to possibly widen the field of nanostructures in HEAs and improve some capabilities of these alloys. In this paper, PM methods applied to HEAs are reviewed, and some possible ways to develop the use of powders as raw materials are introduced.     

难熔高熵合金:制备方法与性能综述

从加工方法、微观结构以及各类性能三方面介绍了难熔高熵合金(Refractory high-entropy alloys,RHEAs),最后对难熔高熵合金的发展和未来进行了展望。以MoNbTaVW为代表的难熔高熵合金在高温下表现出优于传统镍基高温合金的压缩屈服强度,且屈服强度随温度的变化更加缓慢,高温力学性能优异;以MoNbTaVW、MoNbTaTiZr、HfNbTiZr等为代表的难熔高熵合金,与商用高温合金、难熔金属、难熔合金以及工具钢相比,展现出更优的耐磨性能。以W₃₈Ta₃₆Cr₁₅V₁₁合金为代表的难熔高熵合金在辐照后,除了析出小颗粒第二相外,不存在位错环缺陷结构,抗辐照性能优异。提出了难熔高熵合金未来发展的两大方向:建立高通量的实验和计算方法继续探索更多的难熔高熵合金组成和结构模型;探索多场耦合环境下难熔高熵合金的服役行为。      

Big-data analysis of phase-formation rules in high-entropy alloys

Big-data analysis of phase-formation rules of high-entropy alloys (HEAs) was conducted and a phase for-mation rule from a dynamic view was deduced.It was indicated in literatures that cooling rate has a strong influence on the phase formation of HEAs.Higher cooling rate may promote the generation of amorphous phase, and accordingly suppress the formation of intermetallics.Meanwhile, it was also shown that cool-ing rate had little impact on the formation of solid-solution phase.To demonstrate this rule, a series of Fe-CoNi(AlSiB)x HEAs ribbons were fabricated by a melt-spinning technique, and the microstructure, me-chanical, and magnetic properties were also investigated.The results show that all ribbons exhibit disor-dered solid-solution structure.The addition of boron changes the alloy from ductility to brittleness, but without evident change of magnetic properties.The alloy in the nominal composition of FeCoNi(AlSi)0.2 has the best combination of mechanical and magnetic properties.A distinct feature of HEAs in magnetiza-tion was noticed and explained.     

The Structure Formation and Hardness of High-Entropy Alloy Coatings Obtained by Electrospark Deposition

Powder Metallurgy and Metal Ceramics - This paper examines the use of high-entropy alloys (HEAs) as materials for electrospark deposition (ESD). This method is known to produce high-quality...     

Microstructure,Corrosion Behaviour and Microhardness of Non-equiatomic Fe 1.5 CoNiCrCu x (0.5 ≤ x ≤ 2.0) High-Entropy Alloys

The microstructure, electrochemical corrosion behaviour and microhardness of Fe1.5CoNiCrCux (x = 0.5, 1.0, 1.5 and 2.0) high-entropy alloys (HEAs) were investigated by X-ray diffraction (XRD), scanning electron microscopy and an electrochemical workstation. The XRD spectra of Fe1.5CoNiCrCux HEAs confirmed the face-centred cubic solid solution structure and that all specimens consisted of an fcc matrix and a Cu-rich fcc phase. The results of electrochemical corrosion tests showed that Fe1.5CoNiCrCu0.5 HEAs exhibited low corrosion rates owing to their high corrosion potential and low corrosion current density. The major types of corrosion for Fe1.5CoNiCrCux HEAs belong to localised corrosion and pitting, which is attributed to Cu-rich and Cr-depleted phases in the interdendritic region. The microhardness of Fe1.5CoNiCrCux HEAs increases from 142 HV for alloys with x = 0.5 to 190 HV for alloys with x = 2.0.     

Irradiation Behavior in High Entropy Alloys

As an increasing demand of advanced nuclear fission reactors and fusion facilities,the key requirements for the materials used in advanced nuclear systems should encompass superior high temperature property,good behavior in corrosive environment,and high irradiation resistance,etc.Recently,it was found that some selected high entropy alloys(HEAs) possess excellent mechanical properties at high temperature,high corrosion resistance,and no grain coarsening and self-healing ability under irradiation,especially,the exceptional structural stability and lower irradiation-induced volume swelling,compared with other conventional materials.Thus,HEAs have been considered as the potential nuclear materials used for future fission or fusion reactors,which are designed to operate at higher temperatures and higher radiation doses up to several hundreds of displacement per atom(dpa).An insight into the irradiation behavior of HEAs was given,including fundamental researches to investigate the irradiation-induced phase crystal structure change and volume swelling in HEAs.In summary,a brief overview of the irradiation behavior in HEAs was made and the irradiation-induced structural change in HEAs may be relatively insensitive because of their special structures.