Diffusionless transformation of austenite to martensite. To accommodate the elastic strain resulting from the transformation (clamped boundaries) , martensite takes the typical lenticular shape (forming twins). The problem is solved using the Finite Element Method (FEM). The mobility constant on the line y=50 was set to zero, the region with the zero mobility is, however, too small and the transformation easily crosses the 'boundary', forming only high stress concentration points in that region.