Surface relief of alpha '' martensite in a Ti-Mo alloy

The surface relief of alpha " martensite plates in a polycrystalline Ti-4.7 4 at. pet Mo alloy was studied by atomic force microscopy (AFM). The orient ation of matrix grains was measured by electron backscatter diffraction (EB SD), and measured surface tilt angles were compared with calculation by the crystallographic cheery of martensite transformation. The observed maximum tilt angle was close to the predicted value of 7.57 deg. The overall agree ment between measured and calculated tilt angles was improved significantly by taking into account not only the inclination of habit plane to the spec imen surface, but also the shear direction predicted from the theory. The t ilt. angle may vary with the moving direction of the interface unless the h abit plane is perpendicular to the specimen surface. However, this effect w as small in this transformation.