The flow behavior of the solution-treated Mg-3.2Bi-0.8Ca (BX31, wt.%) alloy was systematically investigated during hot compression at different deformation conditions. In the present study, the strain-related Arrhenius constitutive model and dynamic recrystallization (DRX) kinetic model were established, and the results showed that both two models had high predictability for the flow curves and the DRX behavior during hot compression. In addition, the hot processing maps were also made to confirm a suitable hot working range. Under the assistance of a hot processing map, the extrusion parameters were selected as 573 K and 0.5 mm/s. After extrusion, the as-extruded alloy exhibited a smooth surface, a fine DRX structure with weak off-basal texture and good strength–ductility synergy. The newly developed strong and ductile BX31 alloy will be helpful for enriching low-cost, high-performance wrought Mg alloy series for extensive applications in industries.

In this work, we investigate the impact of Bi addition on the heat resistance of as-extruded AZ31 alloy during high-temperature annealing and hot compression. Electron backscattered diffraction (EBSD) technique and quasi in situ scanning electron microscopy (SEM) are used to analyze the evolution of microstructures during high-temperature annealing and hot compression, respectively. The test results show that with a prolonged annealing time, the as-extruded AZB313 alloy exhibited a lower grain growth rate, due to the pinning effect of Mg₃Bi₂ phases distributed at grain boundaries. On the other hand, as the compressive temperature increased, the downtrend of strength is delayed in the as-extruded AZB313 alloy. Thermally stable Mg₃Bi₂ phases dispersed within the grains act as barriers, hindering the motion of dislocations, which not only provides a more effective precipitation strengthening effect, but also increases the resistance to deformation of grains. Moreover, grain boundary sliding can also be restricted by Mg₃Bi₂ phases located at grain boundaries. This work provides a new idea for the development of heat-resistant wrought Mg alloys.

Room-temperature (RT) mechanical anisotropy limits the broad applications of wrought magnesium (Mg) alloys. To weaken the anisotropy, here, we proposed a design idea to create a mixed texture. In the present study, we successfully fabricated the Mg-3Y/Mg-5Li (W3/L5, wt.%) laminated composite, having a mixed texture with a closely orthotropic shape, consisting of an ED-split component in the W3 layer and a TD-split in the L5 layer, via bimetal co-extrusion (ED and TD represent the extrusion and transverse directions, respectively). The mechanical results show that the W3/L5 laminated composite demonstrates a better isotropy at RT, indicating that forming a mixed texture is an effective method to reduce the anisotropy of wrought Mg alloys by bimetal co-extrusion. However, extremely poor interface shear strength, induced by rich O element voids on the interface, triggered poor interface bonding, leading to worse ultimate strength and elongation -to-failure. In future works, controlling co-extrusion parameters or implementing a suitable heat-treatment after extrusion will be necessary to further ameliorate the mechanical properties of the Mg/Mg laminated composites with mixed texture.