密排六方结构高熵合金研究进展

摘要

High-entropy alloys (HEAs) possess excellent properties,and have attracted increasing researchers' interest.It is now generally accepted that the definition of high-entropy alloy is composed at least five principal elements with equimolar ratio or approximately equimolar ratio.Meanwhile,the composition of each element varies from 5％ to 35％.The configuration entropy,mixing enthalpy,atomic radius difference,valence electron concentration and other physical parameters are calculated,combining with CALPHAD phase diagram simulation and first-principles density functional theory (DFT) and AIMD simulation,to predict the phase structure of high-entropy alloys.At present,there are three types of high-entropy alloys,FCC,BCC and HCP high-entropy alloys.HCP high-entropy alloys are scarce and mainly consist of rare earth elements and precious metal elements HCP high entropy alloy.In recent years,it has been found that FCC high-entropy alloys can also be transformed into HCP high-entropy alloys through special treatment methods (such as high pressure).In this paper,the structure,phase formation and properties of HCP high-entropy alloys are reviewed.%高熵合金自问世以来,因其性能独特很快就引起了广大学者的兴趣.对高熵合金的定义,现在大家普遍认为的是由5种及5种以上的主要元素以等摩尔比或近似等摩尔比构成,且每种元素占总成分的5％ ～35％.对配置熵、混合焓、原子半径差、价电子浓度等物相参数进行计算,并结合CALPHAD相图模拟和第一性原理密度泛函理论(DFT)以及AIMD模拟,可用来初步预测高熵合金的相结构.目前,主要有面心立方(FCC)、体心立方(BCC)和密排六方结构(HCP)3大类固溶体高熵合金,其中HCP高熵合金鲜见,主要为稀土元素类和贵金属元素类HCP高熵合金.近几年研究发现FCC高熵合金通过特殊的处理方式(如高压)也可转变成HCP高熵合金.对HCP高熵合金的结构、相形成规律以及性能进行了综述,并讨论了其未来发展趋势.