Microstructure and mechanical behavior of AZ91 Mg alloy processed by equal channel angular pressing

A fine-grained AZ91 alloy was prepared by equal channel angular pressing (ECAP). The evolution of the microstructure and the deformation behavior were investigated as a function of the number of ECAP passes. At room temperature the tensile strength of the ECA pressed specimens is higher than that of the initial state due to the grain refinement and the increase of the dislocation density during ECAP. Above 200 °C the ductility increases due to the increase of the relative fraction of c + a dislocations and also owing to the breakage of the rod-like Al12Mg17 precipitates during ECAP processing.