Improving strength-plasticity synergic of LZ91 alloy by dynamically coherent MgLi2Zn nanoprecipitates

The commercial LZ91 (Mg-9.0 wt%Li-1.0 wt%Zn) alloy was conducted two-stage rolling with 65 % reduction at 250 °C and then additional 20 % reduction at room temperature, and the microstructure and mechanical properties were investigated in the present study. The outcome indicated that a large amount of coherent MgLi₂Zn dynamically precipitated after two-stage rolling, while almost no precipitates were observed for sample deformed at 250°C. This indicated that room temperature rolling promoted the dynamic precipitation of LZ91 alloy. The dynamically precipitated MgLi₂Zn kept a coherent relationship with β-Li, i.e., (220)_MgLi2Zn∥(100)_β-Li and [22̅0]_MgLi2Zn∥[020] _β-Li, which benefited to the simultaneous improvement of strength and plasticity. Furthermore, the more homogeneous distribution of α-Mg and β-Li phases, along with the strong basal texture in the α-Mg phase, positively influences the mechanical response. Consequently, the two-stage rolled sample demonstrated a yield strength of 192 MPa and a fracture strain of 24.7 %. These findings provide new insights into effective strategies for simultaneously improving the strength and plasticity of Mg-Li-based alloys.