| In this paper, microstructures and mechanical properties of an AZ61 mg alloy after cyclic extrusion compression (CEC) process were studied. The effects of the technical factors on the fluidity of the deformation and the main deficiencies of the billet were also investigated. Microstructure evolution was studied by transmission electron microscopy (TEM) to elucidate the grain refinement mechanism. At last the influencing facts on the mechanical properties at room temperature were discussed.Results showed that the effect of grain refinement of CEC process on the AZ61 mg alloy was very apparent. In this paper, the initial grain size 50μm of the AZ61 mg alloy was refined to 0.8μm after CEC 15 passes at 300℃.Microstructures and mechanical properties of the CECed AZ61 mg alloy were controlled by the processing temperature and strain intensity. The effect of grain refinement, yield strength, tensile stress and hardness were increased but the ductility decreased with lowering temperature. The ductility and hardness were improved but strength decreased with the pass number increasing. The refinement effect was limited under a certain condition using CEC and the grains couldn't be refined infinitely with the increase of strain intensity, but the grains become uniform.The effects of the technical factors, such as processing temperature, extrusion speed, friction and lubricant, have an important role on the fluidity during CEC process. The scuffing and crack on the sample surface and the shrinkage cavity in the sample ends were the main deficiencies of the sample after CEC process. And these deficiencies could be inhabited or eradicated by some methods.Grain refinement mechanism of the AZ61 mg alloy during CEC could be regarded as continuous dynamic recovery and recrystallization (CDRR). At the initial stage, increasing dislocations were produced and then tangled dislocations were arranged into dislocation boundaries and sub-grain boundaries. These sub-grain boundaries evolved to...
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