Nanoscale stabilization of metastable phase: thermodynamic model and experimental studies

A thermodynamic model, into which the nanoscale effect is introduced, is established to describe the thermal parameters of metastable phase, as well as their changes with the concentration, temperature and grain size. Based on the model calculations and experiments, the thermodynamic properties and dependence on the grain size are disclosed. Taking the metastable SmCo7 phase for example, the conditions for the single-phase stability and the phase decomposition are studied. The results are important for the control of the phase stability and phase transformation of the metastable-phase alloy.