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

Abstract

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.

Keywords

• Mg–Li alloy
• Wire arc additive manufacturing
• Microstructure
• Mechanical properties