The kinetics of stress relaxation and the effect of pre-annealing amorphous alloys

Abstract

The kinetics of stress relaxation in amorphous alloys are examined quantitatively using the previously reported flow law for these materials. Model relations are derived for tensile and bend tests. The validity of the relations data for FeNiPB and PdCuSi. The effect of pre-annealing on subsequent stress relaxation is also examined. The relaxation rate is found to decrease with increasing pre-annealing time. This decrease is accounted for in the model relations by an increase in the initial viscosity of the test specimens. The rate of viscosity increase during these pre-anneals is lower than the rate of increase measured during the tests. The observation is consistent with a structural relaxation stress threshold, as reported elsewhere. The threshold stress for PdCuSi is at least an order of magnitude smaller than for FeNiPB at the same temperature.