We study a phase-field model, which describes the transformations for
the austenite-martensite and the multiple twinning in Martensite. The
model consists of two nonlinear parabolic equations of second order. We
first show the existence of local solutions to an initial-boundary value
problem by utilizing the Banach fixed-point theorem. Then we verify the
solutions is global. Finally we investigate the regularity and
uniqueness of the solution.