On the metastable liquid miscibility gap in Pd-Ni-P

Abstract

Based on the results of experiments performed at temperatures T ≳ 613 K, a thermodynamic model was recently proposed to explain: (i) the origin of a metastable liquid miscibility gap (MLMG) in Pd-Ni-P, an alloy system with a negative heat of mixing. It originates from the superposition of two distinct liquid Gibbs free energy blades; and (ii) a liquid-liquid phase transition (LLT) just outside the MLMG. Since Gibbs free energy is a function of T, the MLMG was revisited in this work for its T dependence, but this time with T ≲ 613 K. It was found that the MLMG has the shape of a truncated right angle prism, instead of a right angle prism as suggested previously. It is similar to, but not the same as an immiscibility loop in a binary liquid mixture. The revised MLMG is in good agreement with the predictions of the thermodynamic model.