Coalescence of martensite under uniaxial tension of iron crystallites by atomistic simulations

Molecular dynamics simulations are used to study the effects of tensile loading on nucleation and subsequent growth of bcc phase in pure fcc iron. The results show that orientation variant selection occurs during the stress-induced fcc-to-bcc transformation, which leads to the coalescence of neighbouring bcc platelets with identical orientation. The bcc phase nucleates mainly following Nishiyama–Wassermann and Kurdjumov–Sachs orientation relationships with the parent fcc phase. The present simulations contribute to a better understanding of mechanisms controlling mechanically induced martensitic transformation as well as coalescence of bcc platelets in steels.

本研究采用分子动力学模拟，探究拉伸载荷对纯面心立方（face-centered cubic, fcc）铁中体心立方（body-centered cubic, bcc）相的形核与后续生长的影响。结果显示，在应力诱导的fcc向bcc相变过程中会发生取向变体选择现象，该现象会使得具有相同取向的相邻bcc片晶发生聚结。bcc相主要通过与母相fcc相之间的西吉亚马-瓦瑟曼（Nishiyama–Wassermann）和库尔久莫夫-萨克斯（Kurdjumov–Sachs）取向关系实现形核。本项模拟研究有助于深化对机械诱导马氏体相变调控机制以及钢材中bcc片晶聚结行为的理解。