Inhomogeneous microstructure and mechanical anisotropy of multi-directional forged Mg-Gd-Y-Zn-Ag-Zr alloy

In this paper, through multi-directional forging with strain controlled multi-passes under the conditions of initial forging temperature of 480 degrees C and an accumulative strain of 4.4 after 27 forging passes, a bulky Mg-Gd-Y-Zn-Ag-Zr alloy with a size of 460 mm x 260 mm x 160 mm is prepared. The microstructure, texture and mechanical properties of different regions (the center, 1/2R and edge regions) in the alloy bulk are discussed. The results show that the material has undergone significant grain refinement during the multi-directional forging process. Due to the uneven strain and temperature distributions in different regions, inhomogeneous microstructures with different levels of dynamic recrystallization are formed. The average grain size of the center, 1/2R and edge regions is 2.91 +/- 1.77, 3.83 +/- 2.22, and 17.78 +/- 12.24 mu m, respectively. The center region exhibits a doublepeak basal texture, while the 1/2R and edge regions additionally show a rare earth texture component. The tilt of the basal poles in some specific direction causes obvious mechanical anisotropy of the bulk. However, the non-basal rare earth texture component weakens the mechanical anisotropy. The optimum comprehensive mechanical properties are obtained in the center region, with the ultimate tensile strength of 364 MPa, the yield strength of 295 MPa, and the elongation to failure of 4.8%.

Automated summary

In this study, a bulky Mg-Gd-Y-Zn-Ag-Zr alloy was prepared through multi-directional forging under specific conditions. The microstructure, texture, and mechanical properties of different regions were analyzed, showing significant grain refinement but also inhomogeneous microstructures and mechanical anisotropy. The optimum mechanical properties were found in the center region, indicating the complexity of the relationship between microstructure and mechanical performance in the alloy bulk.