Structural disordering in amorphous Pd40Ni40P20 induced by high temperature deformation

The influence of plastic deformation on the structural stale of amorphous Pd40Ni40P20 is investigated by means of tensile test measurements as a function of temperature, strain rate and pre-annealing time. The structural state of the material after the deformation is investigated by means of differential scanning calorimetry (DSC). It is found that amorphous Pd40Ni40P20, when pre-annealed into its metastable equilibrium state, shows a large strain softening effect when deformed at temperatures close to the glass transition temperature. The strain softening effect is less pronounced or even absent in samples that are only briefly pre-annealed. The DSC traces show that the structural slate of the material disorders during the deformation and that the material reaches a strain rate and temperature dependent equilibrium stale, which differs from the thermal equilibrium state. It is shown that the strain softening effect is caused by the creation of additional free volume during the deformation. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.