NiTi₂, a New Liquid Glass

Many endothermic liquid-liquid transitions, occurring at a temperature T_n+ above the melting temperature T_m, are related to previous exothermic transitions, occurring at a temperature T_x after glass formation below T_g, with or without attached crystallization and predicted by the nonclassical homogenous nucleation equation. A new thermodynamic phase composed of broken bonds (configurons), driven by percolation thresholds, varying from ~0.145 to Δε, is formed at T_x, with a constant enthalpy up to T_n+. The liquid fraction Δε is a liquid glass up to T_n+. The solid phase contains glass and crystals. Molecular dynamics simulations are used to induce, in NiTi₂, a reversible first-order transition by varying the temperature between 300 and 1000 K under a pressure of 1000 GPa. Cooling to 300 K, without applied pressure, shows the liquid glass presence with Δε = 0.22335 as memory effect and T_n+ = 2120 K for T_m = 1257 K.