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In this work, Mg98.5Zn0.5RE1(RE = Gd and/or Y) and Mg97Zn1Y2(at%) alloys were subjected to homogenization and equal channel angular pressing (ECAP) to systematically compare the microstructure evolution and mechanical properties. The results indicate that, instead of the lamellar LPSO phases in the as-cast Mg-Zn-Y series alloys, the β-Mg5(Gd, Zn) phases appear in the as-cast Mg98.5Zn0.5Gd1alloy which tend to be dissolved during homogenization. The furnace cooling after homogenization promotes the precipitation of numerous lamellar LPSO phases in all the studied alloys which inhibit the DRX behavior but facilitate the operation of kinking deformation during ECAP for the Mg98.5Zn0.5RE1alloys, especially the Mg98.5Zn0.5Gd1one. After the 5p-ECAP process at 350 °C, the larger density of kink bands, more LAGBs (low-angle grain boundaries) and lower SFB(Schmid factor for basal slip) combine to endow the Mg98.5Zn0.5Gd1alloy with the higher strength-ductility synergy, exhibiting the tensile yield strength (TYS) of 214 MPa and elongation of 9.6%. The Mg97Zn1Y2alloy with the larger volume fraction of interdendritic LPSO phases and dynamically recrystallized (DRXed) regions exhibits the superior ultimate tensile strength (UTS) of 277 MPa and moderate elongation of 7.2%.

Quantifying damage to improve the constitutive models that better account for damage prediction is of great importance in metal forming process. In this study, high-resolution micro-focus X-ray Computed tomography (CT) system, together with loading-unloading tensile test, were employed to quantify the 3D interactions of micro-voids evolution in the biocompatible alloy stainless steel 316L (SS316L). The specimen material was tensile deformed and interrupted at several strain intervals prior to failure, X-ray CT was then performed to quantify the damage evolution via the detected changing in size, number, distribution, and volume fraction of micro-voids (VFMV) after each specified strain increment. Thereby the nature of ductile damage, which involved the dynamic evolution mechanism of the nucleation, growth and coalescence of micro-voids, was revealed. Furthermore, an improved micromechanics-based damage (micro-damage) model considering large deformation condition was implemented into finite element (FE) package ABAQUS for the damage prediction. The damage of the specimen under tensile deformation with a wide range of stress states was predicted and a good agreement with experimental data was achieved in terms of damage distribution and evolution. It is concluded that the findings of this study not only reveal the dynamic evolution mechanism of the micro-voids in the damage process intuitively from the experimental point of view, but also provide more accurate material parameters for the theoretical damage modelling, so as to obtain more convincible damage prediction results in the metal forming process.