铁弹材料孪晶变形的统计行为  

Statistics of twinning deformation in ferroelastics

作　　者：王霄飞 宗洪祥 丁向东[1] 

机构地区：[1]西安交通大学金属材料强度国家重点实验室,西安710049

出　　处：《中国科技论文》2017年第22期2600-2606,共7页China Sciencepaper

基　　金：高等学校博士学科点专项科研基金资助项目(20120201110002);国家自然科学基金资助项目(51320105014;51621063;51231008)

摘　　要：针对铁弹材料孪晶变形过程的微观图像与动力学统计行为之间关系尚不清楚的问题,构筑了基于朗道自由能理论的原子间势函数,并应用于分子动力学模拟。研究结果表明:应变控制下铁弹材料孪晶变形过程中的统计规律和微观形貌均强烈依赖于体系的温度、弹性模量和特征尺寸。铁弹畴形貌的变化在势能曲线上表现为能量噪声。在塑性变形区,其孪晶变形的统计规律会从低温的幂律分布变化到中温的Kohlrausch分布以及高温下的Vogel-Fulcher分布。而在屈服变形区,孪晶变形在较大的温度和应变速率范围内均服从幂律分布,且能量噪声的平均形貌表现为对称的抛物线形。微观形貌分析发现,对于弹性模量较小的铁弹材料,剪切变形可以使其产生高密度的畴界,而且会随试样尺度的减小而增加,这为利用畴界的功能特性提供了1个新的思路。To study the relationship between the microstructure and the statistical behavior of twinning deformation in ferroelastics,an interatomic potential function based on the Landau potential was established and used in molecular dynamics simulations.The results demonstrated that strain-controlled twinning deformation in ferroelastics strongly depended on temperature,elastic modulus and system size.Sudden changes of the domain pattern manifested themselves as"jerks"in the potential energy curve of the sample.In the plastic regime,the statistical behavior of twinning deformation changes from the low-temperature power-law distribution to the Kohlrausch distribution at medium temperature and the Vogel-Fulcher distribution at high temperature.In the yield regime,the statistical behavior of twinning deformation follows power-law statistics in a large range of temperature and strain rate,and the non-spanning avalanches follow the parabolic temporal profiles.The morphological analysis showed that shear deformation can generate high-density domain boundary for the ferroelastic materials with smaller elastic modulus,and the boundary density will increase with the decrease of the sample size.This may shed a new light on the applications of functional domain boundaries.

关 键 词：材料学 铁弹材料 剪切变形 畴界运动 幂律分布 Kohlrausch分布 Vogel-Fulcher分布 

分 类 号：TB34[一般工业技术—材料科学与工程]