Superplastic Behaviour of an Extruded AZ91 Alloy

Plastic deformation of extruded AZ91 magnesium alloy was investigated at various strain rates and in a temperature range of 360-420°C. Samples exhibiting superplastic behaviour were prepared with different thermo-mechanical treatments. Microstructure of samples was observed by light and scanning electron microscopy. The strain rate sensitivity parameter m has been estimated by the abrupt strain rate change method. Possible physical mechanisms of the superplastic flow are discussed.