纳米镍双晶中晶粒和晶界力学性质尺度依赖性理论推导及MD模拟  

Theoretical derivation and MD simulation of size dependent mechanical properties of grains and grain boundaries in nanocrystalline nickel Bi-crystal

作　　者：胡旻浩 孙升 张统一 HU MinHao;SUN Sheng;ZHANG TongYi(Materials Genome Institute,Shanghai University,Shanghai 200444,China)

机构地区：[1]上海大学材料基因组工程研究院,上海200444

出　　处：《中国科学：技术科学》2024年第6期1069-1078,共10页Scientia Sinica(Technologica)

摘　　要：本文基于界面本征应力模型和非线弹性本构,研究了面心立方(FCC)纯镍晶界为∑5的双晶,推导出各向异性双晶模型中晶粒和晶界等效力学性质的尺寸依赖解析公式,开展了分子动力学模拟计算验证了理论解析公式,确定了晶界的材料参数.这些解析公式可以准确预测不同尺寸厚度纯镍(∑5晶界)双晶的力学行为.结果显示,晶界具有比晶粒更小的双轴模量,这导致了双晶的表观双轴模量随模型厚度的增加而增加.该理论模型能够准确描述双晶模型中由晶界本征应力引起的弛豫过程以及模型等效力学性质的尺寸依赖行为,可以直接推广用于其他纳米双晶系统.This paper studied the∑5 grain boundaries of FCC pure nickel and derived the size-dependent analytical formulas of the equivalent mechanical properties of grains and grain boundaries in the anisotropic bi-crystal model based on the interface eigenstress model and nonlinear elastic constitutive model.Molecular dynamics simulations were performed to validate the theoretical analytical formulas and determine the material parameters of the grain boundary.These analytical formulas can accurately predict pure nickel(∑5 grain boundary)with different sizes and thicknesses.The results show that the grain boundary has a lower biaxial modulus than the grain,resulting in an increase in the apparent biaxial modulus of the bi-crystal with model thickness.The theoretical model can accurately describe the relaxation process caused by the eigenstress of the grain boundary in the bi-crystal model and the size-dependent behavior of the equivalent mechanical properties.The theoretical model can be directly applied to other nanocrystalline bi-crystal systems.

关 键 词：纳米晶 尺寸依赖 晶界本征应力模型 非线弹性 

分 类 号：TG146.15[一般工业技术—材料科学与工程] TB383.1[金属学及工艺—金属材料]