Influence of temperature, stress, and grain size on behavior of nano-polycrystalline niobium  

作　　者：晏玉平 张柳亭 张丽攀 芦刚 涂志新 Yu-Ping Yan;Liu-Ting Zhang;Li-Pan Zhang;Gang Lu;Zhi-Xin Tu(School of Acronautical Manufacturing Engineering,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]School of Acronautical Manufacturing Engineering,Nanchang Hangkong University,Nanchang 330063,China

出　　处：《Chinese Physics B》2024年第7期467-474,共8页中国物理B（英文版）

基　　金：Project supported by the Doctoral Scientific Research Starting Foundation of Nanchang Hang Kong University,China(Grant No.EA201903209)。

摘　　要：Atomic simulations are executed to investigate the creep responses of nano-polycrystalline(NC) niobium established by using the Voronoi algorithm. The effects of varying temperature, applied stress, and grain size(GS) on creep properties and mechanisms are investigated. Notably, the occurrence of tertiary creep is exclusively observed under conditions where the applied stress exceeds 4.5 GPa and the temperature is higher than 1100 K. This phenomenon can be attributed to the significant acceleration of grain boundary and lattice diffusion, driven by the elevated temperature and stress levels. It is found that the strain rate increases with both temperature and stress increasing. However, an interesting trend is observed in which the strain rate decreases as the grain size increases. The stress and temperature are crucial parameters governing the creep behavior. As these factors intensify, the creep mechanism undergoes a sequential transformation: initially from lattice diffusion under low stress and temperature conditions to a mixed mode combining grain boundaries(GBs) and lattice diffusion at moderate stress and mid temperature levels, and ultimately leading to the failure of power-law controlled creep behavior, inclusive of grain boundary recrystallization under high stress and temperature conditions. This comprehensive analysis provides in more detail an understanding of the intricate creep behavior of nano-polycrystalline niobium and its dependence on various physical parameters.

关 键 词：creep behavior molecular dynamics simulation activation energy stress exponent nano-polycrystalline niobium 

分 类 号：TG132.3[一般工业技术—材料科学与工程]