Research on Preparation, Microstructures and Mechanical Properties of Hot-Pressed Laminated Mg-Li Alloy Sheets

The LAY821 alloy self-designed is to used to prepare LAY821 alloy sheets for hot-pressing laminated additive manufacturing via extrusion and rolling processes. The microstructures and mechanical properties of the alloy are investigated to provide theoretical and technical foundations for expanding the application of Mg-Li alloy in additive manufacturing. The microstructures are observed by metallurgical microscope and SEM. The phase compositions of the alloy are analyzed by XRD and detected using EDS. The mechanical properties of the alloy are tested by tensile test. The results indicate that the LAY821 alloy as-cast and as-deformed are composed of α-Mg and β-Li phases, and Al₂Y phase distributed along the grain boundaries and among the α-Mg phase. After extrusion, rolling and intermediate annealing treatment, the alloy develops a homogeneous doublephase equiaxial crystal structure, with an average diameter reduction from 11.6 μm to 7.0 μm. The Al₂Y particles are diffusely distributed, withan average diameter reduction from 2.2 μm to 1.0 μm. No new phases are found in the XRD test results. The tensile property of the alloy exhibit 290.26 MPa of UTS, 54.74HV of hardness, and more than 30 % of elonga-tion. The improvement of the mechanical properties is due to the refined equiaxial crystalline structure and the dispersion strengthening effect of Al₂Y. The structure of the LAY821 alloy sheet for the hot-press laminated additive manufacturing is controllable, and the mechanical properties show no obvious anisotropy.