The quaternary Mg–9Li–2Al–0.5Sc alloy (in wt%) was prepared from pure components. After homogenization, the alloy was subjected to severe plastic deformation by KoBo extrusion and cyclic forging leading to grain refinement in the range of 0.5–2 µm of hexagonal close-packed (HCP) α phase. Deformed alloys showed high ultimate tensile strength near 200 MPa and good elongation in the range 30–40% at room temperature (RT). Large elongations close to 200% were obtained during the tensile test at a temperature of 200 °C. Deformed samples showed the presence of multiple voids confirming grain boundary sliding mechanism of deformation. Twins on {10\(\overline{1}\)2} planes were identified using electron backscatter diffraction analysis, being in a good agreement with the earlier observation of Mg–Li and Mg–Sc alloys. Intermetallic phases such as cubic MgSc were identified in deformed alloys mostly within HCP α phase, whereas HCP MgSc₂ particles were observed within body-centered cubic (BCC) β phase. Intermetallic phases were responsible for RT strengthening of alloys and slightly lower tensile elongation during superplastic deformation. Formation of the HCP α phase was observed within the BCC β phase in tensile deformed alloys. Atomic-level nucleation of HCP phase within the β phase was identified by the use of high-resolution transmission electron microscopy technique.

由纯组分制备的Mg-9Li-2Al-0.5Sc四元合金（以重量％计）。均质后，通过KoBo挤压和循环锻造使合金经受严重的塑性变形，导致晶粒细化范围为0.5-2 µm的六方密堆积（HCP）α相。变形合金在室温（RT）下显示出接近200 MPa的高极限抗拉强度，并在30–40％的范围内具有良好的伸长率。在200°C的温度下进行拉伸试验时，可获得接近200％的大伸长率。变形样品显示存在多个空隙，证实了晶界滑动的变形机理。{10 \（\ overline {1} \）上的双胞胎使用电子背散射衍射分析确定了2}平面，这与Mg-Li和Mg-Sc合金的早期观察结果非常吻合。在变形合金中主要在HCPα相内发现了金属间相，例如立方MgSc，而在体心立方（BCC）β相内观察到了HCP MgSc ₂颗粒。金属间相负责合金的RT强化和超塑性变形过程中的拉伸伸长率略低。在拉伸变形合金的BCCβ相中观察到HCPα相的形成。通过使用高分辨率透射电子显微镜技术鉴定了β相中HCP相的原子级成核。