Microstructure and mechanical properties of high pressure die casting AE81 magnesium alloy battery module ends

• The spatial distribution of microstructure and mechanical properties in HPDC AE81 magnesium alloy battery module ends is governed by filling behavior and solidification sequence, with externally solidified crystals (ESCs) decreasing along the flow path toward the overflow gate, leading to finer grains and slightly higher yield strength. • Porosity is the dominant factor controlling ductility and tensile strength; the gate region exhibits the highest porosity (0.74%) and lowest elongation (4.3%) and ultimate tensile strength (218 MPa), while other regions with lower porosity (0.33%-0.39%) achieve elongation of 6%-7% and UTS of 235-242 MPa. • Yield strength follows the Hall-Petch relationship, whereas elongation and tensile strength are negatively correlated with pore volume fraction, providing a quantitative microstructure-property relationship for HPDC magnesium alloys. • The findings elucidate the mechanism behind performance gradients in HPDC magnesium alloys and offer a theoretical basis for designing lightweight components for new energy vehicles, supporting the application of AE81 alloy in critical load-bearing structures.