Flow behaviour of a heat treated tungsten heavy alloy

Flow behaviour of a tungsten heavy alloy was studied in the strain rate-temperature range of 10−5–1/s and 298–973 K, respectively. It was observed in this study that the dislocation motion in tungsten heavy alloy was controlled by a Peierlʹs mechanism at low temperatures (up to 573 K). This was confirmed by the magnitude of apparent activation volume and apparent activation enthalpy as well as TEM observations. Apparent activation enthalpy in the Peierls regime, determined by several methods, was found to vary in between 22 and 37 kJ/mol. An Arrhenius type of constitutive equation was also proposed in the Peierls controlled regime for predicting flow stress as a function of temperature and strain rate. Transition temperature of rate controlling mechanism—from Peierlʹs mechanism to forest mechanism—was determined from the strain rate sensitivity and apparent activation volume estimation at several temperatures. The transition temperature was found to be about 673 K.