Approximate method for phase change in self healing materials

A semi-infinite medium where temperature and concentration are coupled is solved for variable diffusivity phase change. An approximate technique is applied to estimate concentration, temperature, penetration lengths and velocity of change. Surface conditions are held constant whereas diffusivity is allowed to vary slowly corresponding to phase change in the matrix. Penetration lengths are analytically evaluated. A perturbation analysis allows the boundary layer lengths to be estimated, whence the two parameters can be compared. Application to phase change concepts relating to self- healing materials is illustrated.