Microstructure evolution and strengthening mechanisms of Mg-6Gd-4Y-0.5Zn-0.5Zr alloy during hot spinning and aging treatment

The work aims to investigate the optimized spinning temperature of Mg-6Gd-4Y-0.5Zn-0.5Zr alloy and reveal the microstructure evolution and strengthening mechanism of Mg-6Gd-4Y-0.5Zn-0.5Zr alloy during hot spinning and aging treatment. The study shows that the optimized spinning temperature window of Mg-6Gd-4Y-0.5Zn-0.5Zr alloy ranges from 420 degrees C to 460 degrees C, in which the high-performance Mg-6Gd-4Y-0.5Zn-0.5Zr alloy tube with a thickness of 1.5 mm can be successfully fabricated. The multi-pass heating and deformation during hot spinning lead to the precipitation, kinking and break-up of gamma' phase. While the precipitation of gamma' phase aggravates the microstructure inhomogeneity through the thickness of spun tube by restraining dynamic recrystallization. Solid solution strengthening, grain boundary strengthening and shearing strengthening of beta' phase are the dominant strengthening mechanisms of spun Mg-6Gd-4Y-0.5Zn-0.5Zr alloy tube. It is worth noting, finally, that the precipitation of gamma' phase decreases the precipitation density of beta' phase, and thus reduces the age hardening response in the spun tube compared to the extruded Mg-6Gd-4Y-0.5Zn-0.5Zr alloy.

Automated summary

The study investigates the optimized spinning temperature range of Mg-6Gd-4Y-0.5Zn-0.5Zr alloy and the microstructure evolution and strengthening mechanisms during hot spinning and aging treatment. The research shows that the multi-pass heating and deformation during hot spinning influence the microstructure and the dominant strengthening mechanisms include solid solution strengthening, grain boundary strengthening, and shearing strengthening. The precipitation of gamma' phase affects the precipitation density of beta' phase and reduces the age hardening response in spun tube compared to extruded alloy.