Microstructure and tensile properties of the friction stir processed LA103Z alloy

In the present work, a high strength dual-phase MgLi alloy LA103Z was fabricated via friction stir processing (FSP). The microstructure, microhardness and tensile properties of the base metal (BM) and the friction stir processed material were systematically investigated. The β-Li phase underwent complete dynamic recrystallization during FSP, causing significant grain refinement. A large part of the α-Mg phase dissolved under the action of frictional heat. Mg atoms near the grain boundaries formed continuous α-Mg layers around the β-Li grains; part of Mg atoms at β-Li grain interiors formed MgLi2Al phase with Al and Li; and the remaining Mg atoms dissolved in β-Li matrix as solute atoms. Precipitation of MgLi2Al phase and AlLi phase increased during FSP. On account of the solid-solution strengthening and work hardening effect, LA103Z showed excellent mechanical properties after FSP. The ultimate tensile strength (UTS) of LA103Z was significantly increased from 177.9 MPa to 305.5 MPa, improved by 71.7%.