Nucleation of stress-induced martensites in a Ti/Mo-based alloy

The formation of stress-induced α ″ martensite in a metastable β Ti-Mo-based alloy has been studied using X-ray diffraction and transmission electron microscopy. The martensite nucleates heterogeneously at pre-existing sub-grain boundaries by dissociation of the boundary dislocations which bow out on inclined planes. The growth of martensite laths from the resultant stacking faults occurs by the motion of interfacial disconnections: the steps at the cores of these defects account for the apparent discrepancy between the 112 glide plane for the initial partial dislocation and the 334 habit plane for the martensite laths.