STRUCTURAL RELAXATION IN AMORPHOUS PD40NI40P20

Measurements are presented on the change of Young's modulus during structural relaxation of amorphous Pd40Ni40P20. The data are analysed in terms of the mixed model, considering that structural relaxation involves two sub-processes: Chemical Short Range Ordering (CSRO) and Topological Short Range Ordering (TSRO). To describe the kinetics of CSRO and TSRO the Activation Energy Spectrum (AES) model and free volume model are used, respectively. Pd40Ni40P20 is stable enough to bring it to the equilibrium state for both CSRO and TSRO. Therefore reversible relaxation can be shown by performing temperature cycling experiments. Since no theoretical description for the kinetics of TSRO near equilibrium is available, three possible equations are proposed, which were fitted to the Young's modulus data. The obtained parameters were used to describe the glass transition as observed during a DSC experiment. On the basis of the experimental data a choice for one of the three proposed equations could be made. The kinetics of CSRO is rather well described by the AES model.