Fe-Mn-Si-Cr-N形状记忆合金中fcc-hcp相变的细观力学

Mesomechanics of fcc-hcp Martensitic Transformation in Fe-Mn-Si-Cr-N Shape Memory Alloys

摘要:

本文利用Eshelby弹性夹杂理论，针对Fe-Mn-Si-Cr-N形状记忆合金中的马氏体单变体、多变体的弹性应变能以及平行马氏体之间的交互作用进行了理论计算，并比较了间隙原子N对相变细观力学的影响。计算结果表明：N合金化增加了马氏体的应变能，表明马氏体正相变的阻力增加；单变体的应变能远远大于相变的临界驱动力，同时比多变体的应变能大许多，所以热诱发马氏体相变中难以观察到单变体；多变体的应变能与层错切变几率(p)有密切关系，p减小，多变体的应变能降低；基于形状因子(x)的弹性应变能计算显示片状马氏体的应变能最小；而平行马氏体之间的交互作用能与间距相关，在间距增加的开始，这种交互作用减小得快，随后趋于缓和。

Abstract: Based on the Eshelby’s micro-elastic theory, we calculated the elastic strain energy of single variant and multi-variants as well as the interaction energy between two variants in Fe-Mn-Si based shape memory alloys. The influence of N on the mesomechanics of martensitic transformation was studied. The results of theoretical calculations show that N increases the strain energy of phase transition as the resistance term. The strain energy of single variant is much bigger than the critical driving force of fcc-hcp transiton and much more than that of multi-variants, which is the main reason that it is difficult to get the thermal-induced single variant in Fe-Mn-Si based alloys. The elastic strain energy of multi-variants is greatly dependent on the probability of shear (p) and decreases with decreasing p. The calculation related to the shape factor (x) reveals that the thin plate of martensite has a small strain energy compared with the other lens-like martensite. The interaction energy between two martensites reduces quickly with their distance at first and changes slowly when their distance exceeds some critical value.