Mechanisms for the development of tent-shaped and invariant-plane-strain-type surface reliefs for plates formed during diffusional phase transformations

Tent-shaped and invariant-plane-strain type surface reliefs are considered for f.c.c. --> h.c.p., --> b.c.c. --> b.c.c. and b.c.c. --> h.c.p. diffusional phase transformations that produce plate-shaped products. Mechanisms of growth by means of mobile structural ledges with disconnection character are described. Different mechanisms are proposed to account for the two types of surface relief in cases where the transformation product is a single crystal. The predicted relief shapes and relief angles are in good agreement with experimental observations.