Heterogeneous nucleation of martensite near free surface Original Research Article

A theoretical model is proposed which describes heterogeneous nucleation of an embryo of hcp-martensite near a free surface at a tilt grain boundary segment containing some extrinsic dislocations. The total energy gain due to the hcp-embryo nucleation is analysed in detail depending on internal (the distance from free surface and orientation of the grain boundary plane) and external (the temperature and shear stress) conditions. It is shown that the main characteristics of the hcp-embryo nucleation (the energy barrier and critical size) depend strongly on the distance from the free surface.