冲击加载α-Fe中的{332}孪晶

{332} twins in shock-loaded pure iron

本文采用一级轻气炮驱动的平板飞片对α-Fe→ε-Fe相变应力阈值约为13 GPa的工业纯铁进行冲击加载实验,冲击加载压力分别为8.9 GPa和17.5 GPa,分别得到了具有形变特征和相变特征的工业纯铁回收样品。通过透射电镜观察发现,在形变组织和相变组织中都有{332}〈113〉孪晶。形变时,{332}〈113〉孪晶做为二次孪晶在{112}〈111〉孪晶板条中生成,相变时{332}〈113〉孪晶伴随着某些{112}〈111〉马氏体孪晶板条形成。通过分析晶体中各个孪生体系的Schmid因子,得出{332}〈113〉孪生是体心立方结构处于极其不稳定状态(晶格受到严重压缩畸变)时产生的一种变形机制。

Considering the threshold pressure of 13 GPa or so for theα-Fe→ε-Fe phase transition in iron,two pure iron samples were shocked by flyer plates driven by a light gas gun with the shock pressures of 8.9 GPa and 17.5 GPa,respectively.The microstruetures of two shock-loaded samples were studied by transmission electron microscopy(TEM)and the rare{332}〈113〉twins were observed in both of the samples.The{332}〈113〉twins together with{112}〈111〉twins in the sample undergone phase transformations coordinate the process of phase transformations.In the sample without phase transitions,{332}〈113〉twins are formed within{112}〈111〉twin lamella as secondary twins.The analysis of Schmid factors for twinning systems suggested that{332}〈113〉twins are deformation mierostructures when the body-centered cubicα-Fe is under an extremely unstable state.