Martensitic embryo formation at dislocations near surfaces

A two-dimensional continuum model for heterogeneous nucleation of martensite is studied. This nonlinear, nonlocal Landau-type model incorporates slip dislocations into the continuum picture. The elastic strain field of the dislocations occurs in the context of a strongly nonlinear host matrix which models a structural phase transformation. This matrix has more than one stress-free strain. Martensitic embryo structures are observed at temperatures which are much higher than the equilibrium temperature between the parent and product phases. The structure of the embryo as a function of temperature, and the interaction with a nearby free surface which allows for the abrupt appearance of surface relief, are examined.