The increases in strain hardening observed for the in-plane tensile deformation of well-aged magnesium alloy AZ31 are related to a transition from basal to non-basal slip. Based on the results of texture measurements, the double prismatic slip is proposed as the dominant secondary mechanism. The necessary fast strengthening of the basal slip is modelled by an accommodation contribution to the grain boundary resistance. The transition may be consistently modelled by involving the accommodation rather than the production of new sessile dislocations into the evolution laws for dislocation populations.
Fine-grained magnesium alloy QE22 (Mg-2.5wt.%Ag-2.5wt.%RE-0.6wt.%Zr) was prepared from cast ingot which was submitted to a two stages heat treatment. Subsequently the billet was overaged and extruded at high temperature. Samples were deformed at elevated temperatures from 380°C up to 480°C at various strain rates. Microstructure of deformed samples was studied using light and electron microscopy. Conditions for superplasticity of the investigated alloys have been estimated. Possible deformation mechanisms are discussed.
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