Ultra-light Mg-Li alloy with high modulus prepared by cold metal transfer-based directed energy deposition

In this study, the microstructure and properties of a Mg-Li alloy prepared by cold metal transfer-based directed energy deposition using electric arc (CMT DED-arc) were investigated.The as-deposited alloy under different process parameters, as well as the alloy under various processing or heat treatment states, were evaluated. The results indicate that the designed alloy composition exhibits a wide process parameter window employing CMT DED-arc method. The optimal parameters were determined to be wire feed speed of 7 m/min and travel speed of 0.8 m/min, providing the best balance of mechanical properties, surface quality, and structural integrity. Variations in microstructure within different positions of as-deposited thin wall are ascribed to the effect of thermal cycle. The as-deposited alloy achieved excellent comprehensive performance (ultimate tensile strength (UTS)= 224 MPa, elongation= 13.2 %, Young's modulus= 52 GPa, density= 1.539 g/cm3 ). Furthermore, the strength of deposition-solution-treated state exceed that of as-extruded state, reaching UTS of 287 MPa. This work provides insights into optimizing heat input and thermal cycle to improve performance of CMT DED-arc fabricated alloys.