高熵合金增材制造研究现状与展望

Research Progress and Prospects of High-entropy Alloys Made byAdditive Manufacturing

高熵合金是一种新型合金,与传统合金以一种或两种元素为主添加其他元素为辅的设计不同,高熵合金由等原子比或者近等原子比的多种元素组成。高熵合金拥有许多优异的性能,如高强度,高硬度,热稳定性、耐辐照性和耐蚀性,其潜在的工程应用价值引起了人们的广泛关注。目前,电弧熔炼、机械合金化和粉末冶金法是制备高熵合金最主要的方法,但其冷却速率不高,很难制备出具有简单固溶体结构的高熵合金。此外,合金体系一般含有较多价格昂贵的金属元素,电弧熔炼制备块体合金存在成本较高的问题,而机械合金化和粉末冶金法在制备过程中易使合金成分受到污染,这些问题都会限制高熵合金的应用与发展。而先进的增材制造技术(Additive manufacturing,AM)能够有效解决上述问题。如制备过程中无需模具就可以制备出形状复杂的工件;极快的冷却速度,可以得到超细的组织,同时也可以改善元素分布的均匀性,进而提高工件的综合力学性能。因此,高熵合金增材制造在晶粒细化及构件形状复杂度方面拥有不可比拟的优势。本文综述了增材制造高熵合金的研究现状,归纳了增材制造高熵合金的组织结构与性能特点,总结了高熵合金增材制造过程中的缺陷控制与处理工艺,并展望了增材制造高熵合金的进一步发展。

As a new type of alloys,high-entropy alloys(HEAs)are composed of multiple principal elements with equiatomic or near-equiatomic ratio,which is different from the traditional alloys that are added with one or two elements as the principal constituent and supplemented with other elements.These materials have attracted worldwide attention for their outstanding potential value in engineering applications,such as high strength and hardness,thermal stability,irradiation resistance and excellent corrosion resistance.Currently,arc melting,mechanical alloying and powder metallurgy are the most important methods to prepare HEAs.However,as a result of low cooling rate,it is difficult to fabricate HEAs with simple solid solution structures,and high cost and contaminants of those preparation processes limit the potential applications and developments of HEAs.Additive manufacturing(AM)technology can solve these problems effectively,such as complex shape can be prepared without mould.Besides,the fast cooling speed is benefit for obtaining ultra-fine and homogenous structure which can improve the mechanical properties.Thus the additive manufacturing is advanced in high entropy alloys for the grain refinement and shape complexity.Therefore,this paper reviews current research status of HEAs made by additive manufacturing and summarizes the microstructure and perfor-mance characteristics of additive-manufactured HEAs.Furthermore,the defect control and post-treatment technology in the additive manufacturing process of HEAs are discussed in detail,and the development trend of additive-manufactured HEAs is also proposed.