爆炸冲击加载α-Fe中{332}孪晶形成规律的研究

Study on the formation of {332} twins in explosive shock-loaded α-Fe

{332}孪晶作为体心立方晶体的一种反常孪晶,其研究多在亚稳β-Ti合金中进行,而对于α-Fe中的{332}孪晶研究较少。由于在α-Fe中{332}孪晶仅出现在经历了高压冲击加载的样品中,以往的研究主要探讨{332}孪晶能否作为发生α→ε→α可逆相变的标志,但对冲击加载Fe中{332}孪晶的形成条件和形成机制等问题尚不清晰。本文在对多晶铁样品的精细微观结构研究中,重点研究了α-Fe在冲击加载下形成{332}孪晶的压力位置、晶粒取向、形成条件和形成机制,首次在点阵调整的背景下计算了各孪生体系的施密特因子。

{332}twin,a kind of abnormal twins in body-centered cubic(bcc)structure,has been investigated widely in metastableβ-Ti alloys but seldom inα-Fe systems.As the{332}twins inα-Fe only exist in the samples experienced the high pressure shock loading,it has been the important argument whether the{332}twin can be a symbol for the occurrence of the reversibleα→ε→αphase transition or not.However,the occurrence condition and the formation mechanism of{332}twins are still not clear.In this study,the loading direction and the matrix orientation for the occurrence of{332}〈113〉twins were focused,and the formation mechanism of the{332}twins was revealed by considering the lattice compression.The Schmid factors of each twinning systems were calculated based on the adjustment of the lattice parameter.The{332}twinning was preferred in the compressed lattice ofα-Fe.The relationship between{332}twins andα→εphase transition was discussed.