Effect of multi-directional forging in a closed die after extrusion on Gd and Y added AZ61 Mg alloy

Abstract

In this study, 0.5 and 1 wt.% Gadolinium (Gd) and Yttrium (Y) rare earth elements were added to the AZ61 magnesiumalloy. The alloys were exposed to extrusion at 375 degrees C, followed by multi-directional forging in a closed die at 400 degrees C. Themicrostructural changes and mechanical properties of the alloy were examined. The addition of rare earth elements and theapplied mechanical processes led to a significant reduction in grain size in the AZ61 cast alloy. The addition of Gd and Ypromoted the formation of the Al2(Y,Gd) intermetallic structure, which contributed to heterogeneous nucleation andincreased hardness. The extrusion and multi-directional forging processes further contributed to afine-grained, equiaxedmicrostructure. As a result of the grain refinement, notable improvements in the mechanical properties were observed.In mechanical tests, samples with 0.5% Gd and 0.5% Y achieved the highest tensile strength (290 MPa) and hardness values(113 HV). In contrast, a slight decrease was observed with 1% additions, indicating that the optimal rare earth elementcontent is 0.5%.