Xingwang Duan

To study the effect of reduction ratio on the interfacial evolution, microstructure, and mechanical properties of Al/Mg/Al laminated composites, hot rolling experiments of Al/Mg/Al laminated composites with 30%, 40%, 50%, and 60% reduction ratios were carried out at 400 °C. The interfacial morphology, phase composition, microstructural evolution of the Mg layer, and the mechanical properties of the laminated composites were analyzed. The results showed that a continuous intermetallic compound layer mainly composed of Mg ₁₇ Al ₁₂ and Mg ₂ Al ₃ was formed at the Mg/Al interface at each reduction ratio. The peeling strength and mechanical strength of the laminated composites increased first and then decreased with the reduction ratio. The peeling strength reached a peak value of 23.04 N/mm, the ultimate tensile strength reached the highest value of 244.09 MPa, the yield ratio decreased to the lowest value of 0.72, and the plastic strain ratio ( r ) reached the highest value of 1.96 at 50% reduction ratio. At this time, the dynamic recrystallization of the Mg layer was the most complete, the grains were significantly refined and the texture was weak. In summary, the laminated composites showed a better match among interfacial bonding, microstructural evolution, and comprehensive mechanical properties under 50% reduction ratio at 400 °C.

To investigate the effect of annealing temperature on the forming and mechanical properties of hot‐pressed Ti/Al/Mg/Al/Ti (LMCS), LMCS was prepared using a hot‐pressing process at a pressure of 175 MPa and 480 °C for 60 min. The interface structure and formability were controlled by annealing at 200, 250, 300, and 350 °C for 1 h. The corresponding performance indicators were tested by tensiling, cupping, and T‐peeling tests and analyzed and characterized using scanning electron microscopy, electron backscatter diffraction, and X‐ray diffraction. The results show that at an annealing temperature of 300 °C, the basal texture is weak, and static recrystallization leads to uniform grain growth. The smaller average nuclear orientation difference (KAM) results in a decrease in dislocation density and local strain. Good formability is achieved at 300 °C, with a minimum ultimate tensile strength and yield strength of 189.02 and 237.75 MPa and a maximum elongation and cupping value of 3.62% and 4.88 mm, respectively. This provides theoretical guidance for the development of practical annealing processes for LMCS.

In the process of thermal deformation, the microstructure and texture evolutions of AZ80A magnesium alloy have an important influence on its properties. In order to reveal the evolutions of microstructure and texture of AZ80A magnesium alloy during hot deformation, isothermal compression tests were performed on a Gleeble-3800 thermal simulator at a temperature range of 623 K∼723 K, a strain rates range of 0.001 s⁻¹∼1 s⁻¹, and a deformation rate of 20%∼60%. Based on the analysis of the true stress-true strain curves under the given deformation conditions, the hyperbolic sinusoidal constitutive model and dynamic recrystallization (DRX) kinetics model were established by regression method, respectively. The DRX behavior, microstructure and texture evolutions during the thermal compression were then analyzed by optical microscopy (OM) and electron backscattered diffraction (EBSD). The results show that an increasing deformation temperature and decreasing strain rate greatly support the development of DRX of AZ80A magnesium alloy. As the deformation rate increases, DRX of AZ80A alloy is gradually and more sufficiently developed, and the dominated deformation mechanism is gradually transformed from the {0001} base slip to { 10 1 ¯ 0 } cylinder slip. Moreover, the low-angle grain boundaries (between 5° and 75° in deformation rate of 20%) gradually transform into large-angle grain boundaries (between 50° and 90° in deformation rate of 60%). Besides, the texture is gradually transformed from a base texture paralleled to compression direction to a texture perpendicular to compression direction, where twinning, rather than slip, is the main deformation mechanism. The results in this study provides a guidance in the hot forming process of AZ80A magnesium alloy.

The microstructures of as-cast AZ80A magnesium alloy before and after homogenization treatment were studied. The flow behaviors of the homogenized alloy under different deformation conditions were studied by isothermal compression tests. Based on the flow stress-strain curves of the homogenized alloy, the constitutive model was established by the strain compensation method. The strain rate sensitivity index maps with different strains were constructed to quantify the dynamic recrystallization softening behavior of the homogenized alloy. Based on this, the influence of deformation temperature and strain rate on strain rate sensitivity index and dynamic recrystallization microstructure evolution were studied. The results show that both increasing homogenization temperature and holding time are beneficial for the β-phases to dissolve and alloying elements to diffuse. It is concluded that the proper homogenizing parameter of as-cast AZ80A magnesium alloy is 683 K for 20 h. Both the increase of deformation temperature and the decrease of strain rate are beneficial to the increase of strain rate sensitivity index. The region with an index greater than 0.22 corresponds to dynamic recrystallization softening zone and has good deformation properties.