定向凝固Al_(7)(CoCrFeMnNi)_(93)高熵合金微观组织演化及单晶生长  

Microstructure Evolution and Single Crystal Growth of Al_(7)(CoCrFeMnNi)_(93)High-Entropy Alloy Prepared by Directional Solidification

作　　者：王强力 钟宏[1] 李斗 郑晗煜 胡忠武[2] 高选乔 张文[2] 李双明[1] Wang Qiangli;Zhong Hong;Li Dou;Zheng Hanyu;Hu Zhongwu;Gao Xuanqiao;Zhang Wen;Li Shuangming(State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China;Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China)

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072 [2]西北有色金属研究院,陕西西安710016

出　　处：《稀有金属材料与工程》2024年第6期1616-1625,共10页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51674201)。

摘　　要：采用定向凝固技术研究了Al_(7)(CoCrFeMnNi)_(93)高熵合金微观组织的演化规律,以自然竞争生长法制备出胞状和树枝状亚结构单晶体,并研究了亚结构和取向对高熵合金单晶体纳米力学性能的影响。结果表明,Al_(7)(CoCrFeMnNi)_(93)高熵合金在定向凝固过程中界面更容易失稳,其平-胞界面转变速率小于1μm/s,胞-枝界面转变速率范围约为2~5μm/s。合金的一次、二次枝晶间距均随着定向凝固速率增加而逐渐减小,并分别与抽拉速率满足指数关系。定向凝固后,该合金枝晶干区域富集Co、Cr和Fe元素,而熔点较低的Mn、Ni和Al元素倾向于富集枝晶间区域。以自然竞争法获得的胞状、树枝状亚结构单晶的取向分别为[214]和[213]。纳米力学性能数据表明偏析行为造成的亚结构对单晶体的弹性模量和硬度影响较小,而晶体取向对单晶体的弹性模量影响较大,对硬度值影响较小。Microstructure evolution of Al_(7)(CoCrFeMnNi)_(93)high-entropy alloy was studied by directional solidification technique.Single crystals of high-entropy alloy with cellular and dendritic substructures were prepared by the natural competitive growth method.The effect of substructure and orientation on the nano-mechanical properties of high-entropy alloy single crystals was studied.The results show that the growth interface of Al_(7)(CoCrFeMnNi)_(93)high-entropy alloy is more prone to destabilization during directional solidification.Its planar-cellular solidification interface transition rate is less than 1μm/s,and the cellular-dendritic solidification interface transition rate ranges from 2 to 5μm/s.The primary dendrite arm spacing and the secondary dendrite arm spacing of the alloy decrease gradually with the increase in directional solidification rate and satisfy the exponential relationship with the withdrawal rate.After directional solidification,the elements of Co,Cr,and Fe are enriched in the dendrite region,while the elements of Mn,Ni,and Al with lower melting temperatures tend to be enriched in the inter-dendrite region.The orientation of the cellular and dendritic substructures single crystal obtained by the natural competition method are[214]and[213],respectively.The data of nano-indentation mechanical properties show that the substructure caused by segregation behavior has little effect on the elastic modulus and hardness of single crystals,while the crystal orientation has a greater influence on the elastic modulus of single crystals but little effect on the hardness value.

关 键 词：定向凝固 高熵合金 微观组织演化 亚结构 单晶生长 

分 类 号：TG244[金属学及工艺—铸造]