Calculation of the Activation Energy for Super Plastic Flow in Zn-22Al Alloy

Abstract

Abstract The application of the unified physics is the way to understand the phenomenology and mechanics of super plastic flow (SPF). In this scenery, the main proposed in this work is to establish the effect of grain size and thermomechanical conditions on the activation energy for super plastic flow (Qspf) in Zn-22Al eutectoid alloy by applying the quantum mechanics and relativistic model (QM-RM) proposed by Muñoz-Andrade. Analyses on the experimental results reported before by some authors, it is shown for grain size of 0.35 μm that the calculated Qspf by using QM-RM for grain boundary sliding is 55.669 kJ/mol at 303 K and strain rate of 1 s−1. These results are in closed agreement with the value of Qa = 54 kJ/mol reported previously by using the theoretical and conventional methodology set up by Mohamed and Langdon. However, for grain size of 0.8μm, the calculated Qspf is 67.864 kJ/mol at 473 K and strain rate of 1×10−2 s−1. Furthermore, in order to understand the phenomenology and mechanics of SPF in Zn-22Al eutectoid alloy, the variation of the activation energy with the temperature; stress and strain rate is analyzed in association with coupled mechanisms during SPF, such as grain boundary sliding, cooperative grain boundary sliding and self-accommodation process related to the microstructure.