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Effects of annealing temperature and annealing time on the microstructure, interfacial bonding properties and mechanical properties of alternate α/β Mg-Li alloy composite plates by accumulative roll bonding (ARB) were investigated. Due to the large reduction, a part of the relatively harder Mg-5Li-1Al alloy is embedded into the softer Mg-12Li-1Al alloy to achieve metallurgical bonding in the process of composite rolling. The optimum annealing temperature of the composite plate is 350 °C or 400 °C. At the same time, the formation mechanism of the interfacial diffusion region was discussed, and results show that there exist two diffusion regions, diffusion layer 1 and diffusion layer 2. The diffusion layer 1 is mainly composed of Li3Mg7 phase, and the diffusion layer 2 is composed of Li0.92Mg4.08 phase. The interfacial bonding ability of Mg-Li alloy composite plate first increases and then decreases with the increase of annealing temperature and annealing time. Compared with the composite plate processed by one pass ARB, the annealing time of the composite plate processed by six passes ARB increases due to the increase of cumulative strain, and the optimum annealing process is at 400 °C for 30 min.

Ultrafine-grain and high-strength Mg-5Li-1Al sheets were prepared by accumulative roll bonding (ARB) process. Evolution of microstructure and mechanical properties of ARB-processed Mg-5Li-1Al sheets was investigated. Results show that, during ARB process, the evolution of deformation mechanism of t Mg-5Li-1Al alloy is as follows: twinning deformation, shear deformation, forming macro shear zone, and finally dynamic recrystallization (DRX). The grain refining mechanism changes from twin DRX to rotation DRX. With the increase in ARB cycles, strength of the Mg-5Li-1Al sheets is enhanced, whilst elongation varies slightly. With the increase in rolling cycles, anisotropy of mechanical properties decreases. It is conclusive that strain hardening and grain refinement dominate the strengthening mechanism of Mg-5Li-1Al alloy.

Mg–5Li–1Al (LA51) and Mg–5Li–1Al–0.5Y (LA51–0.5Y) alloys were smelted and rolled with different accumulated strains (36% and 68%) and rolling temperatures (373 K and 573 K). The microstructure, mechanical properties, fracture morphology and texture of the specimens were investigated. Results show that, due to the PSN (particle stimulate nucleation) mechanism, the addition of 0.5 wt.% Y improves the deformation resistance and weakens the basal texture of LA51 alloy. The effect of Y on UTS (ultimate tensile strength) of as-rolled alloys is more obvious than that of the as-cast alloy. Accumulated strain and rolling temperature could influence the twinning number, slip systems and DRX (dynamic recrystallization), thus affecting the microstructure and mechanical properties of the alloy. Under the proper combination of the above factors, the as-rolled LA51–0.5Y alloy with an accumulated strain of 68% at 573 K possesses the best comprehensive mechanical properties. Keywords: Mg–Li alloy, Accumulated strain, Rolling temperature, Microstructure, Mechanical property, Texture

Accumulative roll bonding (ARB) technique is used to manufacture fine-grained and high-strength Mg–8Li–3Al–1Zn alloy. Then, investigate the microstructure and mechanical properties. Results show that, the ARB-processed sheet possesses good bonding performance. The ARB refines the grains and causes the phase distribution to be scattered. With the increase of ARB passes, the σ0.2, σb, and hardness values are enhanced, whereas the elongation value first decreases, then slightly increases with the increase of ARB passes. The ARB5 sheet possesses the smallest grain size (about 3 µm) and the best comprehensive mechanical properties, the tensile strength, elongation, and hardness are 287.02 MPa, 12.5%, and 77.2 HV0.05, respectively.

Mg-9Li-6Al(LA96) and Mg-9Li-6Al-2La(LA96-2La), after solution treatment, were aged at 50C and 150C, respectively. The microstructure evolution and hardness variation of the alloys under different aging parameters were investigated. The results show that the morphology of MgLi2Al(h) phases in LA96 changes from short and rod like to particulate during the aging period, and the size of particulate phase becomes larger and larger in the late aging period. The small, stripy a phases precipitate from b phases. The microstructure evolution leads to a continuous decrease in hardness. A temporary increase of hardness appears in the process of aging treatment at 150C because of the precipitation of AlLi phases. The addition of La inhibits the variation of MgLi2Al morphology and the precipitation of small and stripy a phases in b phases, and it makes the decrease rate of hardness become lower in the process of aging treatment.

Mg–8Li–(0–3)Ce alloys were prepared with a vacuum melting method. The microstructure and mechanical properties of these alloys were studied. It is found that addition of Ce obviously refines the grain size of the alloy and leads to the formation of intermetallic compound (Mg12Ce). Extrusion and rolling processes lead to the improvement of mechanical properties. The alloys after extrusion have better mechanical properties than those after rolling.