Direct estimation of stacking fault energy by thermodynamic analysis

An attempt is made to calculate the stacking fault energy by a thermodynamic analysis. It is shown that the stacking fault energy is equal to the difference in bulk free energies between f.c.c. and h.c.p. phases in non-magnetic metals. On the other hand, the magnetic surface energy contribution to the stacking fault energy is significant in magnetic materials. It is also confirmed that the high value of the stacking fault energy at the f.c.c./h.c.p. transition temperature in cobalt base alloys and austenitic stainless steels can be explained by considering the magnetic effect. The temperature and compositional dependence of the stacking fault energy is evaluated in many systems. Excellent agreement is found between the calculated and observed values.