NiTi, a New Liquid Glass.

Many endothermic liquid-liquid transitions, occurring at a temperature T above the melting temperature T, are related to previous exothermic transitions, occurring at a temperature T after glass formation below T, 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 with a constant enthalpy up to T. The liquid fraction Δε is a liquid glass up to T. The solid phase contains glass and crystals. Molecular dynamics simulations are used to induce, in NiTi, 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 = 2120 K for T = 1257 K.