Trapping mechanism of metastable β-Ga disclosed by its lattice stability optimization and nucleation behavior exploration

Abstract

Application of gallium-based liquid metals below 273 K calls for design of novel metastable materials with exceptionally low melting points. It is crucial to develop the thermodynamic database of metastable phases and to unveil their trapping mechanism. In this work, the thermodynamic assessment of metastable β-Ga and its lattice stability were evaluated by integrating experimental and ab-initio thermodynamics. We demonstrated that the lattice stability expression derived from a high-order modified Einstein modeling with anharmonic correction provided the most reliable and the most accurate description hitherto. Thereafter, the critical radius and the work for nucleation were derived by applying our optimized expressions of lattice stability and surface energy. Thereby the capturing of β-Ga at nano sizes and high supercooling were well explained. And it was confirmed that the classical nucleation theory played an important role in trapping metastable β-Ga phase. Furthermore, the significance of surfaces and interfaces in solidification process were highlighted. This work sheds light on designing metastable liquid metals with low melting points. Moreover, it provides a novel workflow for future studying of metastable multicomponent alloys.