Properties of severe plastically deformed Mg alloys

In this present investigation, mechanical properties of bulk Mg alloys synthesized by mechanical alloying (MA) and equal channel angular pressing (ECAP) were investigated. For mechanically alloyed samples, a dramatic increase in yield strength to 498 MPa has been achieved after 5 h milling. Strain softening accompanied by increased ductility of the longer milled samples is observed through the gradual decrease in yield strength. The lowest yield strength of 200 MPa was observed after 30 h milling while the elongation at fracture was dramatically increased to 45%. The average grain size was about 75 nm for specimens milled for 30 h. In ECAP, the accumulation of redundant shear strain and dynamic recrystallisation refine the microstructure while increasing the material's yield strength. Consequently, ductility is reduced. The mechanical properties of the Mg alloy are also found to be sensitive to the processing temperature at which ECAP is conducted and to the number of ECAP passes.