Structural relaxation in metallic glasses

Structural relaxation in several transition metal based metallic glasses ha s been studied using differential scanning calorimetry (DSC), X-ray diffrac tion (XRD), electrical resistivity, acoustic emission and Mossbauer spectro scopy techniques. Annealing of metallic glass below the crystallization tem perature gives rise to discontinuous changes in electrical resistance. Thes e changes are accompanied by acoustic emissions. The latter process provide s an indication for the viscous flow in the matric;. In diverse alloy compo sitions, it has been observed that changes in electrical resistivity which begin instantly with the onset on isothermal annealing do not follow diffus ion kinetics. Mossbauer experiments also show that neither long range diffu sion nor the formation of a new phase occurs as a result of annealing. It i s concluded that viscous flow is the mechanism for structural relaxation in duced by isothermal annealing and short range ordering during this process is also a consequence of the viscous how process. (C) 2001 Elsevier Science B.V. AU rights reserved.