Characterization of porosity and its effect on the tensile properties of Mg-6Gd-3Y-0.5Zr alloy

Microstructure investigations and static uniaxial tensile tests of Mg-6Gd-3Y-0.5Zr (GW63) alloys containing varied content of porosity were carried out to disclose the relationship between porosity and tensile properties. Here, a qualitative analysis was performed by relating the tensile properties with porosity level, which was relevant to porosity content and assessed by X-ray detector. Besides, both analytical (i.e., critical local strain model) and empirical methods were applied to quantitatively investigate the influence of porosity on tensile properties, based on the projected area of porosity on the fracture surface. The results showed that two types of porosity and three typical regions on the fracture surface were identified. Both ultimate tensile strength (UTS) and elongation-to-failure (EL) decreased with porosity level increasing. Besides, a great scatter of EL of each porosity level was observed. The critical local strain model was testified not applicable for GW63 alloys to calculate the tensile properties. Instead, strong quantitative correlations between tensile properties and porosity area fraction were obtained through the empirical approach.