The stability of martensite in Cu-Zn alloys.

Abstract

The enthalpy and entropy difference between the β phase and the martensite has been calculated for Cu-Zn binary and ternary alloys using a description in terms of pairwise chemical interaction energies. It is shown that the concentration dependence of M3 is mainly determined by fourth neighbour pair interactions. This result is also supported by the analysis of the critical stress which is necessary to transform the orthorhombic martensite to a fcc ordered lattice. In contrast to the strong effect which long range order has on the enthalpy of transformaron, the entropy difference has been found to be quite insensitive to order.