A calorimetric investigation on the kinetics of solute segregation to partial dislocations in Cu–3.34at%Sn

The kinetics of solute segregation to partial dislocations in a Cu–3.34at%Sn alloy was studied using a phenomenological approach with differential scanning calorimetry and isothermal calorimetry. The material, severely deformed by repeated bending, presented an excess of dissociated edge dislocations with a dislocation density amounting to about 9.8×1014 m−2, calculated using an authorsʹ prior model together with calorimetric recrystallization trace analysis. The kinetics was found to be ruled by two overlapping mechanisms: diffusion of solute atoms mostly through dislocations pipes at the beginning and medium stages of reaction process, acting together bulk solute diffusion at that stages and later on. Bulk solute diffusion increases as the reaction proceeds, as shown then by increasing values of apparent activation energy in the reaction. The exponent of the Mehl-Johnson-Avrami equation used in the phenomenological description was successfully fitted to a time-temperature dependent function increasing in agreement with the apparent activation energy behaviour, as may be expected.