Microstructure of superplastic QE22 and EZ33 magnesium alloys

Superplastic deformation has been observed in the QE22 and EZ33 magnesium alloys prepared by the special thermornechanical procedure. The microstructure was analysed by the scanning and transmission electron microscopes before and after deformation. Samples with the grain size of similar to 1 pm were deformed at elevated temperature at the strain rates from 1 x 10(-4) to 1 x 10(-3) s(-1). Microstructure analysis showed an existence of particles in the grain boundaries. This precipitates are very stable even at high temperature deformation. These heat resistant phases are very probably responsible for the grain stability and also prominent superplastic behaviour of alloys studied. (C) 2008 Elsevier B.V. All rights reserved.