A Calculation of the Elastic Constants and the Effect of its Anisotropy on the Martensitic Transformation in 3/2 Electron Compounds

Abstract

It has been assumed that the elastic anisotropy has an important effect on the martensitic transformation temperature, Ms, in 3/2 electron compounds (β-phase alloys) consisting of the noble metals. The elastic constants, 1/2 (C11-C12) and C44, were calculated as a function of the electron concentration, e/a, from the X-ray data by Zirinsky on Au-Cd alloys which represent a typical martensitic transformation of the 3/2 electron compounds. It appears that the following four factors which have a large effect upon the elastic constants in the noble metals-based alloys; (a) the electron concentration, e/a, (b) ionic radius, (c) quenched-in excess vacancies and (d) ordering. These factors have also an important influence upon the change in Ms. The experimental results on the martensitic transformation of Au-Cd alloys were found to be in good agreement with this prediction.