Tailoring the microstructure and texture to achieve high strength in a high-Al content Mg alloy by stepless-temperature-reduction ECAP

Abstract

A stepless-temperature-reduction equal channel angular pressing (ECAP) approach showing a good advantage over the customary one (i.e., isothermal ECAP) in microstructure refining and texture modifying of Mg–Al binary alloy was proposed. The average grain size of Mg–13Al (wt.%) alloy processed by this new approach is substantially refined down to 790 nm, accompanying with the presence of high-density dynamically precipitated β phase particles whose average size is approximately 219 nm. Moreover, a strong “hard” preferred orientation is developed after processing, namely, an appreciable portion of the grains have their c-axes tilted by about 81° with respect to the extrusion direction. Eventually, the ultrafine grain structure and “hard” crystallographic orientation confer the Mg–13Al alloy with a high tensile yield strength of 367 MPa. The novel ECAP approach given here can apply to other Mg alloys wherein precipitation strengthening is insignificant.