Theory of spontaneous amorphization of metastable crystalline phases

Abstract Some metastable crystalline alloys show spontaneous amorphization and subsequent re-crystallization during transformation. This means that the amorphization is the result of competitive transformation kinetics in which both the metastable amorphous and stable crystalline phases are formed in parallel. However, the amorphous phase formation rate is much larger than that of the crystalline phase, so that in the first stage of transformation the resulting phase is amorphous. In the paper a theoretical description of the kinetics of these two processes is presented, taking into account the competitive formation of crystalline and amorphous phases on the boundaries of grains of the initial phase. The equations of nucleation and growth of the competitive phases are solved. The general approach is applied to the amorphization transformation kinetics in Cd–Sb alloys. The numerical analysis of equations of kinetics and the comparison with experimental results are carried out for Cd 43 Sb 57 .