Kinetics of the martensitic f.c.c.→ h.c.p. transformation in CoCrMo alloy powders

The kinetics of isothermal martensìtìc nucleation in CoCrMo alloy powders is monitored. It is shown that a linear relation exists between the activation energy for martensite formation and the chemical free energy for the f.c.c. → h.c.p. transition. The nucleation kinetics is governed by the thermally activated motion of partial dislocations and the interaction between the Shockley partials and short range obstacles (stacking faults intersections and solute clusters).