摘要
基于纳米晶热力学特性表征函数,将纳米晶热力学性质对晶界迁移的影响引入Cellular Automaton算法,对纳米晶粒长大行为进行了定量化和可视化的仿真研究.模拟结果表明,纳米晶粒长大的动力学与传统粗晶材料不同,在恒温条件下,纳米晶粒的长大指数n不是常数(传统粗晶材料的晶粒长大指数n=2为常数),随纳米晶粒长大过程的进行,n值从1.70至6.59发生变化.作为纳米晶粒长大的驱动力,纳米晶界的过剩自由能与纳米晶粒尺寸的变化直接相关.由于纳米晶材料强烈的小尺寸效应,纳米晶组织的热力学性质较大地影响纳米晶界的结构和能量状态,从而影响纳米晶粒长大的动力学特征.因此,只有结合纳米晶热力学特性的仿真研究才能获得对纳米晶粒长大行为本质性的认识.
Based on proposed analytical model describing the thermodynamic functions of nanograin boundaries, the thermodynamic features of nanograin boundaries were introduced into the Cellular Automaton algorithm. With the hybrid model, the quantitative and visual simulations of nanograin growth have been carried out. The simulation results show that the nanograin growth kinetics is different from the normal grain growth kinetics in conventional polycrystalline materials. The nanggrain growth exponent （n） is not a constant as in the polycrystaUine metals which equals 2, but changes with the growing process, which has a range of 1.70-6.59. The excess free energy of the nanograin boundaries is the driving force for nanograin growth, which is closely related with the grain size. The thermodynamic features of nanograin boundaries strongly affect the energy state of the nanocrystalline materials hence the nanograin growth kinetics, as a result of the nanoscale effect. For the simulations of nanograin growth the thermodynamic features of nanocrystalline materials should be introduced.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2008年第4期495-500,共6页
Acta Metallurgica Sinica
基金
国家自然科学基金项目50401001和50671001
北京科技新星计划项目2004B04资助~~
关键词
金属纳米晶
纳米晶粒长大
元胞自动机方法
热力学
metal nanocrystalline, nanograin growth, Cellular Automaton method,thermodynamics
