摘要
研究了纳米晶CoNiCrFeMn高熵合金在拉伸过程中塑性变形产生的空洞裂纹的演化进程与其拉伸力学性能的相关性,比较了服役温度和平均晶粒尺寸对纳米晶CoNiCrFeMn高熵合金和纳米晶Ni的拉伸力学性能、微结构演化以及位错总长的影响。结果表明:服役温度从低温10 K升到高温1000 K时多晶CoNiCrFeMn高熵合金比单晶CoNiCrFeMn高熵合金屈服应力的降幅分别为14.9%、13.1%和17.4%;多晶Ni比单晶Ni屈服应力的降幅分别为38.9%、30%和32.3%。同时,随着服役温度的提高,纳米晶高熵合金和纳米晶镍的弹性模量和屈服强度呈线性下降趋势。晶界缺陷诱导的内应力和空洞裂纹缺陷,使多晶镍的屈服应力比单晶高熵合金百分比的降幅更大;空洞裂纹缺陷的产生和其外形尺寸改变是材料服役力学性能急剧下降以及纳米晶高熵合金和纳米晶镍拉伸力学性能显著差异的根本原因。拉伸载荷使多晶材料晶粒内先产生极多的内秉堆垛层错,且随着温度的升高大晶粒易分化出细小晶粒并出现晶粒细化的纳观现象。同时,受内应力的诱导多晶高熵合金和多晶镍更易在晶界边缘产生新位错,且位错分布与内应力分布的趋势一致;随着温度的升高热胀冷缩使多晶材料的晶界范围进一步扩张,使应力的分布区域比在低温下更大。
The tensile performance of high-entropy nanocrystalline-and single crystal-CoNiCrFeMn alloy,as well as polycrystalline-and single crystal-Ni metal,was comparatively assessed,while the evolution of their microstructures and the deformation induced difects such as dislocations,voids and cracks etc.with the deformation process and temperature was searched in an attempt to reveal the relationship between their mechanical performance and the aforesaid evolution.Results show that when the temperature lifting from 10 K to 1000 K,the yield stress of the high-entropy nanocrystalline CoNiCrFeMn alloy decreases by 14.9%,13.1%and 17.4%,whose corresponding temperature is 10 K,300 K and 1000 K respectively,in comparision to those of the high-entropy single crystal ones;While the tensile strength of the polycrystalline Ni decreased by 38.9%,30%and 32.3%of that for single crystalline Ni,whose corresponding temperature is 10 K,300 K and 1000 K respectively;Likewise,the elastic modulus and yield strength of the high entropy nanocrystalline alloy and nanocrystalline nickel decrease linearly with the increasing temperature.However,the overall decrease percentage of the value for yield stress of the polycrystalline nickel is greater than that of the high entropy single crystal alloy,owing to the exist of internal stresses,cracks and cavities induced by grain boundary defects of the former.It is thought that the geometry shape and size of the formed cavities and cracks are the fundamental cause responsible to the sharp decline of the mechanical properties of the similar materials in practical application,and also to the significant difference of the tensile mechanical properties between the high entropy nanocrystalline alloy and the nanocrystalline nickel.The applied tensile load may result in the formation of a large number of stacking faults within grains of polycrystalline materials,and thus the large grains are easy to be differentiated into fine grains with the increasing temperature,in other word,to realize the grain refinement.In addition,the high entropy polycrystalline alloy and polycrystalline nickel are more likely to generate latest dislocations at grain boundary edge induced by internal stresses,hence,the dislocation distribution is consistent with the internal stress distribution.With the increasing temperature,the distribution area of grain boundaries within polycrystalline materials will be further expanded due to thermal expansion,therefore,the area with internal stresses will enlarge accordingly,in comparison to that at lower temperature.
作者
陈晶晶
占慧敏
吴昊
朱乔粼
周丹
李柯
CHEN Jingjing;ZHAN Huimin;WU Hao;ZHU Qiaolin;ZHOU Dan;LI Ke(School of Mechanical and Electrical Engineering,Nanchang Institute of Technology,Nanchang 330044,China;School of Computer and Information Engineering,Nanchang Institute of Technology,Nanchang 330044,China;Beijing Institute of Space Launch Technology,Beijing 100048,China)
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2023年第8期614-624,共11页
Chinese Journal of Materials Research
基金
南昌理工学院机械表/界面摩擦磨损与防护润滑校级研究中心,江西省教育厅科学技术研究项目(GJJ2202705,GJJ212101,GJJ219310)
南昌市重点实验室建设项目(2020-NCZDSY-005)
南昌理工学院校级课题(NLZK-22-07,NLZK-22-01)。
关键词
金属学
空洞裂纹
晶粒尺寸
温度响应
拉伸力学性能
分子模拟
metallography
void crack
grain size
temperature response
tensile mechanical performance
molecular simulation
作者简介
陈晶晶,男,1989年生,硕士;通讯作者:陈晶晶,chenjingjingfzu@126.com,研究方向为机械表界面摩擦磨损与润滑防护。
