Growth dynamics study of the martensitic transformation in Fe-30 pct Ni alloys: Part II. Computer simulation of martensitic growth

Abstract

The growth of the shear-type martensitic transformation in an Fe-30 pct Ni alloy has been studied using molecular dynamics (MD) computer simulations. A semiempirical method is used to construct the interatomic potential including the conduction electron volume-dependent en-ergy to fit the experimental data of both austenite and martensite phases. A volume variation method is derived to calculate the volume-dependent forces in cooperation with the pairwise forces to govern the motions of atoms. The effect of strain conditions on the growth rate of the martensitic transformation has been investigated by varying the average atomic density in the simulation box. The computer simulations indicate that the increasingly severe strain conditions result in a decrease of the growth velocity during the transformation, which is, in turn, related to the loss of the net driving force of the transformation. The MD computer simulations also reveal some microscopic features of the martensitic transformations such as the highly aniso-tropic mobility of the interface associated with its orientation and the interface structure, which favors a sharp transition between two phases as opposed to a glassy transition region.