High-strength GWZ1031K alloy with gradient structure induced by surface mechanical attrition treatment

Abstract

This work investigated the surface mechanical attrition treatment (SMAT) on the microstructure and mechanical properties of the Mg-10Gd-3Y-1Zn-0.4Zr (GWZ1031K, wt%) alloy. Before SMAT, the studied alloy with bimodal-grained structure was prepared by extrusion and aging. The results showed that the traditional bimodal-grained structure transformed into gradient structure including two characteristic areas after SMAT: (a) the severely deformed layer containing nanograins and sub-micron grains; (b) the deformed coarse grained layer, where the banded structure is distorted in this region. The gradient structure induced by SMAT can improve the mechanical properties of GWZ1031K alloy obviously. After SMAT for 10 min, the micro-hardness of the surface increases from 117 HV to 137 HV because of the grain refinement. The alloy also exhibited superior mechanical properties at room temperature, the yield strength (YS) is 427 MPa, the ultimate tensile strength (UTS) is 562 MPa and the elongation is 4.1%. The findings indicate that SMAT is a suitable method for solving structural optimization problems and achieving high strength in Mg-RE alloys.