FeCoCrNiCu高熵合金纳米压痕力学响应的分子动力学模拟  

Nanoindentation Mechanical Properties of FeCoCrNiCu High Entropy Alloys:A Molecular Dynamics Study

作　　者：孙业伟 张路明 马胜国 张团卫[1] 辛浩 SUN Yewei;ZHANG Luming;MA Shengguo;ZHANG Tuanwei;XIN Hao(Institute of Applied Mechanics,Taiyuan University of Technology,Taiyuan 030024,China;Shanxi Key Laboratory of Material Strength and Structural Impact,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学应用力学研究所,太原030024 [2]太原理工大学山西省材料强度与结构冲击重点实验室,太原030024

出　　处：《太原理工大学学报》2023年第3期562-569,共8页Journal of Taiyuan University of Technology

基　　金：国家自然科学基金资助项目(12102291);山西省自然科学基金资助项目(201901D111088);北京理工大学爆炸科学与技术国家重点实验室资助项目(KFJJ21-07M)。

摘　　要：采用分子动力学(MD)模拟建立FeCoCrNiCu高熵合金纳米压痕模型,从杨氏模量、位错行为等方面对FeCoCrNiCu高熵合金进行相关力学性能分析。研究分析了纳米压痕过程中温度和加载速度对合金基体变形的影响。经模拟以及数据拟合发现,杨氏模量与实验结果近似一致;纳米压痕过程依次经历弹性-塑性阶段,进入塑性阶段后基体内部产生位错,随着压头的不断深入,位错不断形核扩展最终成环;由于高熵合金复杂的元素组成以及应变梯度效应,剪切应变在合金体内的分布是不均匀的。加载速度对弹性阶段影响不大,但会对位错的增长产生影响,临界塑性压深也会随加载速度的增大而增大;温度对高熵合金的变形有着显著影响,温度升高会使原子运动加剧,基体易于变形。低温下压痕力明显上升,这是由于低温本身会降低原子迁移率,同时也利于孪晶产生,使基体进一步强化。Nanoindentation of FeCoCrNiCu high entropy alloys(HEAs)was simulated by molecular dynamics(MD)simulation to investigate the mechanical properties of HEAs in terms of Young’s modulus,dislocation,and shear strain.And the effects of loading rates and temperatures on the deformation of alloy matrix were studied.The young's modulus obtained by fitting was approximately consistent with the experimental results.In nanoindentation,HEAs underwent elastic deformation first,and then began plastic deformation.Dislocations continuously nucleated and expanded under the indenter and eventually formed dislocation loops.Owing to the complex element composition and the strain gradient effect,the distribution of shear strain in the alloy was not uniform.The loading rate had an effect on the growth of dislocation,and the critical plastic depth also increased with the increase of loading rate.The deformation of HEAs was significantly affected by temperature.With the increase of indentation temperature,atoms moved more violently,and the matrix was easily deformed.The indentation force increased obviously at low temperature,because the low temperature itself reduced the atomic mobility and facilitated the formation of twins,which further strengthened the matrix.

关 键 词：高熵合金 分子动力学 纳米压痕 温度 加载速度 

分 类 号：O341[理学—固体力学]