Effect of Equal-Channel Angular Extrusion on Microstructure and Mechanical Properties of Mg-1Gd and Mg-2Zn Alloys
The effects of equal-channel angular extrusion on the microstructure and mechanical properties of two binary alloys,Mg-lGd and Mg-2Zn were studied by OM and EBSD.The results show that under the same extrusion conditions,Mg-2Zn alloy fully recrystallizes,resulting in grain growth and coarsening,and the strength and plasticity do not change with the number of extrusion passes.Mg-1Gd alloy only partially recrystallizes after extrusion,with a microstructure consisting of fine dynamic recrystallized grains and deformed grains.With the increase in the number of extrusion passes,the degree of recrystallization increases,leading to a doubling of the tensile strength and plasticity of Mg-1Gd alloy.This is related to the greater inhibition of recrystallization and grain growth by the solute atom Gd compared to Zn.The recrystallized grains have a dispersed orientation,while the grains that do not recrystallize in Mg-lGd alloy have a c-axis orientation that deviates 45° from ED to TD,which is consistent with the detection of macroscopic texture.A large number of small-angle grain boundaries form within the grains,and rotations around the c-axis occur on both sides of these boundaries,gradually evolving into large-angle boundaries.
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