The as-cast Mg-6.5Li-xY-yZn alloys (Mg-6.5Li-0.8Y, Mg-6.5Li-0.8Y-0.3Zn and Mg-6.5Li-1.0Y-1.0Zn) were extruded at 553 K with an extrusion ratio of 25:1 and a constant extrusion speed of 1.6 mm/s. The microstructure and corrosion behavior of as-extruded Mg-6.5Li-xY-yZn alloys were studied by microstructure observation, weight loss test, hydrogen evolution test and electrochemical test in present work. The microstructure shows that the Mg-6.5Li-0.8Y alloy contains alpha-Mg, beta-Li and Mg2Y phase, the Mg-6.5Li-0.8Y-0.3Zn alloy is composed of alpha-Mg, beta-Li and X phase (Mg12ZnY, LPSO phase) and the Mg-6.5Li-1.0Y-1.0Zn alloy consists of alpha-Mg, beta-Li and W phase (Mg3Zn3Y2). The corrosion results indicate that the combining addition of Y and Zn can improve the corrosion resistance of Mg-6.5Li alloys and Mg-6.5Li-0.8Y-0.3Zn alloy with LPSO phase possesses the best corrosion resistance. The surface microstructure of test alloys after immersed in 3.5 wt% NaCl solution for 48 h, showing that the Mg-6.5Li-0.8Y alloy has the most corrosion pits while the Mg-6.5Li-0.8Y-0.3Zn alloy has the least corrosion pits due to the minimal micro-galvanic formed on its surface. (C) 2020 Elsevier B.V. All rights reserved.

Mg-8Li-1Al-0.5Sn (wt%) alloy was prepared by casting and deformed by hot extrusion in this study. The microstructure and mechanical properties of as-cast and extruded alloys were studied by OM, SEM, XRD, and the tensile test. The results show that the Mg-8Li-1Al-0.5Sn alloy consists of α-Mg (hcp), β-Li (bcc), LiMgAl2, Mg2Sn, Li2MgSn phases. After hot extrusion, the β-Li phase was refined, and Mg2Sn compounds were distributed uniformly in the matrix. The yield strength and ultimate tensile strength of extruded specimen reach to 240MPa and 322MPa respectively at room temperature. At 423K (150°C), the ultimate tensile strength arrives at 220MPa for extruded alloy. The strength of Mg-8Li-1Al-0.5Sn alloy is higher than many traditional Mg-Li alloys.

In this study, as-cast alloy Mg-9Li-3A1-2.5Sr (LAJ932) ingots were extruded at different temperatures using an extrusion ratio of 28, and the underlying microstructural evolution and mechanical behavior were investigated. The results show that grains in the extruded LAJ932 alloy are much finer than those in the as-cast one, which indicates that the microstructural evolution during extrusion is governed by dynamic recrystallization. With increasing extrusion temperature, the grain size of the extruded alloy increases, and the strength decreases whereas the elongation increases. The alloy extruded at 250 degrees C possesses the highest strength of 238 MPa with an elongation of 18.1%, whereas(1) the alloy extruded at 350 degrees C has the largest elongation of 21.6% with a strength of 208 MPa. The differences in microstructure characteristics between the alpha-Mg phase and beta-Li phase in the alloy extruded at 250 degrees C suggest that continuous dynamic recrystallization (CDRX) occurs in the alpha-Mg phase during extrusion whereas the microstructure evolution in beta-Li phase is governed by discontinuous dynamic recrystallization (DDRX). DDRX occurs in alpha-Mg phase to some extent and the fraction of DDRX grains in the alloys increases with increasing extrusion temperature. (C) 2018 Elsevier B.V. All rights reserved.

Hot deformation behavior of an as-extruded duplex structured Mg-9Li-3Al-2.5Sr alloy is investigated via hot compression tests conducted at 200-350 degrees C with strain rate of 0.001-1 s(-1). The flow behavior of Mg-9Li-3Al-2.5Sr alloy can be described accurately by hyperbolic sine constitutive equation and the average activation energy for deformation is calculated as 143.5 kJ/mol. Based on a dynamic materials model, the processing maps of Mg-9Li-3AI-2.5Sr alloy which describe the variation of power dissipation efficiency are constructed as a function of temperature and strain rate. The processing maps exhibit an area of discontinuous dynamic recrystallization occurring at 280-300 degrees C with strain rate of 0.001-0.01 s(-1), which corresponds to the optimum hot working conditions. Copyright (C) 2016, The editorial office of Journal of Materials Science & Technology. Published by Elsevier Limited.