Microstructural Analysis of Butterfly-Type Martensite by Using EBSD

Electron backscatter diffraction (EBSD) is effective method to investigate crystal orientation distribution in materials. Especially, EBSD has given a lot of novel knowledge for phase transformation of Fe and Fe alloys. In this study, microstructural analysis of martensite (α′) with butterfly shape in Fe-Ni alloys are performed by conventional EBSD observation and in-situ EBSD observation during tensile test. By using EBSD, it is found that crystal orientation in the butterfly-type α′ is locally changed. Moreover, the butterfly-type α′ has both features of lath and lenticular α′. This comes from the change of accommodation process for shape strain of the butterfly-type α′ during its growth. Furthermore, the tensile deformation influences the change of accommodation process for shape strain of the butterfly-type α′. From the obtained results, formation process of the butterfly-type α′ is discussed.