Microstructure and mechanical properties of Mg–Li alloys fabricated by wire arc additive manufacturing

Gas tungsten arc welding (GTAW) based wire arc additive manufacturing (WAAM) process is first used to fabricate a thin wall of LA103Z magnesium-lithium alloy. Results indicate that the grain size of the LA103Z thin-walled bottom region significantly differs from that of the middle and top regions. The main phases present in the LA103Z thin wall include α-Mg and β-Li phases, along with some particulate second phases (LiAl, Li2MgAl). Moreover, the thermal action of the subsequent sedimentary layer promotes the transformation of β-Li→α-Mg+β-Li and Li2MgAl →LiAl phase. The mechanical properties of the LA103Z thin wall are affected by a combination of factors such as grain size, the proportion of the α-Mg phase, and morphology. The tensile strength of the LA103Z thin-walled samples in the bottom, middle, and top regions is measured at 195.1 MPa, 181.8 MPa, and 201.4 MPa, respectively, with corresponding elongation percentages of 3.4%, 7.3%, and 12.4%. In the building direction, the tensile strength is recorded as 177.7 MPa, with an elongation percentage of 7%. The study reveals that WAAM-GTAW has the potential to make magnesium-lithium alloys more widely available.