Relaxation kinetics and mechanical stability of metallic glasses and supercooled melts

Metallic glasses are characterized by a rather complex viscoelastic response and the occurrence of the glass transition, while the atomistic origins are still poorly understood. Using a realistic CuTi model glass we employ global and local elasticity tensors for a thorough analysis of relaxation kinetics and mechanical stability. We obtain strong indication that (i) alpha relaxation is governed by an underlying process (identified as slow beta relaxation) which resembles diffusion in its temperature dependence, (ii) glasses reveal intrinsic mechanical instabilities, which are closely linked to collective shear events within shear transformation zones, and (iii) glass transition can be understood as a percolation transition of mechanically unstable regions.