Prediction of solid-state amorphizing reaction using effective driving force

It is proposed that the nucleation and growth of the amorphous phase through the solid-state amorphizing reaction in thin-film diffusion couples can be predicted by using the concept of effective driving force. The effective driving force consists of two factors: (i) the thermodynamic driving force given by maximum free-energy difference between the physical mixture of binary elements and the amorphous phase (ΔG_max), and (ii) the kinetic factor given by a ratio of the effective radius of the interstitial site in the host matrix to the atomic radius of the diffusing species (R_m/d). From the comparison of reported experimental results, it is shown that the criterion of effective driving force holds well for predicting the nucleation of the amorphous phase in metal/silicon systems as well as that of metal/metal systems. In addition, the concept of effective driving force holds well for predicting the growth tendency of the amorphous phase in metal/silicon systems.