HREM OBSERVATIONS OF CONTINUOUSLY CHANGING INTERMEDIATE STRUCTURES BETWEEN FCC AND BCC AT THE AUSTENITE-MARTENSITE INTERFACE

Continuous lattice change from f.c.c. to b.c.c. as a function of subna nometric distance is observed near the austenite-martensite interface in an Fe-Ni-Mn alloy transformed isothermally at low temperature. From detailed analysis of such lattice changes, it is concluded that the l attice deformation proposed by Kurdjurnov and Sachs: is the most appro priate one. The Bogers-Burgers mechanism on which the Olson-Cohen nucl eation model is based is found to be inadequate to explain the present observations.