RELATIONSHIP BETWEEN STACKING FAULT ENERGY AND SHAPE MEMORY IN PRIMARY SOLID SOLUTIONS.

Abstract

Evidence is presented that in austenitic stainless steels, the shape memory effect is not due to the occurrence of the gamma to alpha prime martensitic transformation. To obtain shape memory, the steel must be deformed above its Ms temperature (which should preferably be below minus 196 degree C) and at as low a temperature as possible. Shape memory is also favored by elements which decrease the stacking fault energy of the steel. Shape memory is attributed to the reversal of stacking faults produced by low temperature deformation. To confirm this hypothesis, it has been demonstrated that shape memory exists in copper f. c. c. solid solutions of low stacking fault energy.