Microstructure evolution and mechanical properties of Mg94Sn3Al2Zn1 alloy under different extrusion processes

Abstract

Mg alloys offer potential value in the research and application of structural materials, optimizing superior extrusion processes for this purpose has been a major emphasis. This study examined the impact of five extrusion processes (two conventional forward extrusion and three innovative ES techniques) on the microstructure evolution and mechanical properties of Mg94Sn3Al2Zn1 (wt.%) alloys. Findings show that the ES technique dramatically improved the plasticity of the alloy whereas retaining its high strength. Among all the ES samples, the ES-105 sample exhibited the best tensile properties at room temperature. Mechanical properties differ significantly based on microstructure evolution, with CDRX and DDRX being the primary mechanisms for microstructure evolution in Mg94Sn3Al2Zn1 alloys. Compared to the FE samples, the ES samples are distributed with finer and more homogeneous DRXed grains, and the texture components obviously modify, distinguishing from the basal texture in the FE samples, which exhibit recrystallization texture after extrusion. The as-extruded alloy contains mainly Mg2Sn and a small amount of Mg17Al12 as well as denser and finer second phases in the ES samples. These second phases are crucial in weakening the texture by facilitating the recrystallization process via PSN mechanism, thereby inhibiting the growth of the DRXed grains.