Relationship between free volume and glass transition temperature of Zr ₅₀Cu ₅₀ metallic glasses based on molecular dynamics simulation

Atomic structure evolution and diffusivity during the cooling of Zr ₅₀Cu ₅₀ metallic liquid are studied by molecular dynamics (MD) simulation. Based on the theory that free volume is equal to the volume difference between the amorphous materials and their crystalline counterpart, a new method of annihilating rate of free volume has been developed and applied to predict the critical microscopic glass transition temperature. The predicted critical temperature T _c was 969.5 K, which is close to the MCT (mode-coupling theory) value of 978.4 K, and the caloric glass transition temperature T _g was 731 K, which is also close to the value of 725 K determined from the curve of average atomic volume with temperature. Without calculation of diffusion coefficients at a serial of specified temperatures, the developed method is more convenient than former methods to calculate T _c and T _g.