Synthesis, microstructural evolution, and compaction behavior of Mg 30 -Al 25 -Ti 25 -Li 15 -Si 5 lightweight high-entropy alloys synthesized via mechanical alloying

Abstract In this research work, Mg 30 -Al 25 -Ti 25 -Li 15 -Si 5 lightweight high-entropy alloys (LWHEAs) were synthesized via mechanical alloying (MA) with different milling times of 0, 5, 10, and 20 h. The X-ray diffraction (XRD) results of MAed powders exhibited the formation of intermetallic phases (Mg 2 Si and Al 12 Mg 17 ) and nanocrystalline structures with prolonged milling times, enhancing diffusion, lattice strain, and grain refinement. Scanning electron microscopy powder surface morphology, EDAX analyses, and elemental mapping were examined to confirm the structural refinement and uniform elemental distribution, though lithium detection remained challenging. Further, based on XRD results, peak broadening models (Scherrer, Williamson–Hall, and size–strain plot) were employed to estimate the crystallite size and lattice strain, with the Williamson–Hall model showing the highest accuracy. Compaction studies at room and high temperatures (275 and 550°C) with pressures up to 200 MPa demonstrated improved densification and mechanical integrity, attributed to the phase formation and structural refinement during milling. A relative density of 94.42% was achieved at 200 MPa and 550°C in the 20 h MAed sample due to improved atomic diffusion-driven densification, grain-boundary diffusion, and decreased work-hardening effect. The nanocrystalline nature, refined grain morphology, and enhanced densification emphasize the potential of Mg 30 -Al 25 -Ti 25 -Li 15 -Si 5 LWHEAs for lightweight structural applications in aerospace, automotive, and advanced manufacturing industries.