Bian Zhenyu, Song Jian, Liu Pingping, Wan Farong, Lei Yu, Wang Qicong, Yang Shanwu, Zhan Qian, Chen Liubiao, Wang Junjie
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
China Classification Society Certification Co., Ltd., Beijing 100006, China.
Materials (Basel). 2022 May 26;15(11):3794. doi: 10.3390/ma15113794.
The thermoelastic martensitic transformation and its reverse transformation of the Cu-Al-Mn cryogenic shape memory alloy, both with and without compressive stress, has been dynamically in situ observed. During the process of thermoelastic martensitic transformation, martensite nucleates and gradually grow up as they cool, and shrink to disappearance as they heat. The order of martensite disappearance is just opposite to that of their formation. Observations of the self-accommodation of martensite variants, which were carried out by using a low temperature metallographic in situ observation apparatus, showed that the variants could interact with each other. The results of in situ synchrotron radiation X-ray and metallographic observation also suggested there were some residual austenites, even if the temperature was below M, which means the martensitic transformation could not be 100% accomplished. The external compressive stress would promote the preferential formation of martensite with some orientation, and also hinder the formation of martensite with other nonequivalent directions. The possible mechanism of the martensitic reverse transformation is discussed.
对有压缩应力和无压缩应力的Cu-Al-Mn低温形状记忆合金的热弹性马氏体相变及其逆相变进行了动态原位观察。在热弹性马氏体相变过程中，马氏体在冷却时形核并逐渐长大，在加热时收缩至消失。马氏体消失的顺序与形成顺序正好相反。利用低温金相原位观察装置对马氏体变体的自协调进行观察，结果表明变体之间可以相互作用。原位同步辐射X射线和金相观察结果还表明，即使温度低于Ms，仍存在一些残余奥氏体，这意味着马氏体相变不能100%完成。外部压缩应力会促进具有一定取向的马氏体优先形成，同时也会阻碍其他非等效方向马氏体的形成。文中讨论了马氏体逆相变的可能机制。
