Latest research advances on magnesium and magnesium alloys worldwide

Plastic deformation and heat treatment of Mg-Li alloys: a review

Effect of lithium content on the mechanical and corrosion behaviors of HCP binary Mg–Li alloys

Achieving excellent superplasticity in an ultrafine-grained QE22 alloy at both high strain rate and low-temperature regimes

The microstructures, mechanical properties, deformation mechanism and cavitation growth of Mg-10.2Li-2.1Al-2.23Zn-0.2Sr alloy subjected to multidirectional forging and rolling (MDFR) were studied to examine the deformability of the Mg-Li alloy. X-ray diffraction (XRD) results confirm the existence of α (Mg) and β (Li) phases and Mg17Al12, Al4Sr and LiMgAl2 intermetallic compounds. Studies of the microstructures reveal that a thin banded-grained microstructure with a grain size less than 3.75 µm is obtained via MDFR and annealing at 523 K for 1 h. There were significant grain refinements. The maximum elongation to failure was 712.1%, and this was obtained in the current alloy at 623 K with a strain rate of 1.67 × 10−3 s−1. The strain rate sensitivity exponent and the activation energy for deformation were estimated to be 0.884 and 91.9 kJ/mol, respectively. This indicates that the rate-controlling deformation mechanism under the aforementioned condition is grain boundary sliding controlled by lattice diffusion. Experimental cavity observations show the existence of cavity interlinkage or stringers. A new plasticity-controlled cavity growth rate equation considering cavity interlinkage was established, and a cavity growth diagram was constructed. The diagram prediction is consistent with the experimental results. In addition, fractographs show that the intergranular fracture is a ductile fracture mechanism. At room temperature, the ultimate tensile strength of 242 MPa and the elongation of 23.59% were obtained in the present alloy.

Superplasticity of a dual-phase-dominated Mg-Li-Al-Zn-Sr alloy processed by multidirectional forging and rolling

A novel dual-phase-dominated fine-grained (5.5 μm) Mg-6.4Li-3.6Zn-0.37Al-0.36Y alloy was fabricated by multidirectional forging and rolling (MDFR); its mechanical properties and microstructural evolution were investigated. The ultimate tensile strength of 286 MPa and elongation of 31.8% were demonstrated in this alloy. The Portevin–Le Chatelier effect was observed in cold-rolled alloy. During MDF, the dominant grain refinement mechanisms of the α-Mg phase are mechanically fragmented grain refinement and deformation-induced in-situ dynamic recrystallization (DRX) grain refinement. However, the dominant grain refinement mechanism of the β-Li phase is deformation-induced in-situ DRX grain refinement. In later stage, thermally activated grain coarsening occurs in both phases. X-ray diffraction analyzes reveal the existence of α-Mg and β-Li phases, Al2Y, and MgLi2Al intermetallic compounds in the MDF state and the existence of α-Mg and β-Li phases, Al2Y, Al12Mg17, and MgLiZn intermetallic compounds in the cold-rolled state. Transmission electron microscopy analyzes show that high-density dislocation pile-up, dislocation tangle, subgrains, and MgLiZn particles exist in the cold-rolled alloy and raise the tensile strength. Texture analyzes reveal that strong {0001} basal texture or basal fiber of α-Mg phase exists, but the texture intensities in this alloy are not high. Annealing does not produce new texture component. A Hall-Petch model was established in this alloy: yield strength = 11.83 + 351.89 times minus square root of grain size. The relationship between critical resolved shear stress and resistance to deformation was modeled. Static recrystallization and grain coarsening during annealing were discussed.

Mechanical properties and microstructural evolution in a superlight Mg-6.4Li-3.6Zn-0.37Al-0.36Y alloy processed by multidirectional forging and rolling

Guoqiang Xue

Papers

Superplasticity of a dual-phase-dominated Mg-Li-Al-Zn-Sr alloy processed by multidirectional forging and rolling

Mechanical properties and microstructural evolution in a superlight Mg-6.4Li-3.6Zn-0.37Al-0.36Y alloy processed by multidirectional forging and rolling