Incorporating dislocation variables into Mohamed's and Kawasaki-Langdon's deformation mechanism maps containing superplasticity mechanism regimes

Deformation mechanism map (DMM) is a useful tool to depict pictorially the deformation mechanisms and to elucidate the nature of material flow in creep and superplasticity. In this paper, the number of dislocations and the dislocation density inside the grain and at the grain boundary were incorporated into Mohamed's and Kawasaki-Langdon's DMMs in an attempt to give their distribution. It is found that in superplasticity or Region II regime, whether or not the dislocations exist inside the grain depends on the Burgers vector compensated grain size and the shear modulus compensated stress. In the DMMs, the number of dislocations at the grain boundary is about one fifth as much as that inside the grain. The dislocation forecasts in Coble creep and dislocation creep regimes are consistent with the thoughts of Coble and Weertman mechanisms. A new DMM containing the dislocation density was proposed with Zn-22 wt% Al eutectoid alloy as the subject and its prediction is in good agreement with some of available experimental evidences. (C) 2015 Elsevier B.V. All rights reserved.