Microstructural evolution and mechanical properties of Mg-Zn-Y-Zr alloy during friction stir processing

Here, a Mg-6Zn-1Y-0.5Zr casting was subjected to friction stir processing (FSP). The effect of thermal and mechanical effects on the microstructural evolution and mechanical properties of the casting was studied. FSP resulted in remarkable grain refinement, dissolution and dispersion of intergranular eutectic I-phase (Mg3Zn6Y) networks and strong basal texture. Based on mechanically activated effect of FSP, I-phase transformed to W-phase (Mg3Zn3Y2) and dispersed particles with a core-shell structure formed. The increase of travel speed caused greater grain refinement and higher fraction of dispersed particles, which greatly improved yield strength, ultimate tensile strength, and elongation, 93.1%, 53.0%, and 151.4% higher than that of the cast materials, respectively. (C) 2016 Elsevier B.V. All rights reserved.