On the determination of shear angle in martensitic transformations

Yang et al.'s pioneer work on the relationship between the shear angle and the surface relief angle of martensitic transformation (MT) was discussed, and its limitation was pointed out. Furthermore, a new universal method to determine the shear angle in MT was developed in this work. Firstly, the surface relief angle accompanying MT was measured by atomic force microscopy. Secondly, a trial-and-error method and an extended procedure were proposed for the calculation of the indices of the sample free surface. And finally, the limitation of Yang et al.'s method was eliminated using this method combined with Bergeon et al.'s model. The calculated shear angles for both fcc → hcp and fcc → bct MT using the current method were in good agreement with the theoretical values of the shear angles predicted by phenomenological theory of martensitic crystallography.