Zhongtao Jiang

Balancing strength and ductility remains a central challenge in low-alloy Mg–Al–Ca–Mn alloys. In this study, a Mg–12Al₂Y master alloy was added to Mg–1.2Al–0.8Ca–0.4Mn to obtain nominal Al₂Y contents of 0, 1, 3, and 5 wt.%. The composites were prepared by stir casting and hot extrusion. In the as-cast condition, Al₂Y particles occurred both within α-Mg grains and in interdendritic regions; the 3 wt.% Al₂Y composite had the finest structure. Extrusion produced a bimodal microstructure of fine dynamically recrystallized (DRXed) grains and coarse unrecrystallized regions, and fragmented Al₂Y and Al₂Ca particles formed stringers along the extrusion direction. The 1 wt.% Al₂Y composite showed the highest tensile yield strength (346 MPa) and ultimate tensile strength (361 MPa), with an elongation of 5.8%. At 3 wt.%, the yield strength, ultimate tensile strength, and elongation were 316 MPa, 332 MPa, and 11.8%, respectively, representing the best strength–ductility balance among the compositions examined. Increasing the Al₂Y content to 5 wt.% raised the elongation to 12.6% but reduced the strength because of particle agglomeration and microstructural coarsening. The variation in mechanical response is discussed in relation to recrystallized grain size, retained deformation, texture, and particle distribution. Within the processing window examined here, master-alloy addition offers a practical route for controlling Al₂Y reinforcement in Mg–Al–Ca–Mn composites.

Balancing strength and ductility remains a central challenge in low-alloy Mg–Al–Ca–Mn alloys. In this study, a Mg–12Al₂Y master alloy was added to Mg–1.2Al–0.8Ca–0.4Mn to obtain nominal Al₂Y contents of 0, 1, 3, and 5 wt.%. The composites were prepared by stir casting and hot extrusion. In the as-cast condition, Al₂Y particles occurred both within α-Mg grains and in interdendritic regions; the 3 wt.% Al₂Y composite had the finest structure. Extrusion produced a bimodal microstructure of fine dynamically recrystallized (DRXed) grains and coarse unrecrystallized regions, and fragmented Al₂Y and Al₂Ca particles formed stringers along the extrusion direction. The 1 wt.% Al₂Y composite showed the highest tensile yield strength (346 MPa) and ultimate tensile strength (361 MPa), with an elongation of 5.8%. At 3 wt.%, the yield strength, ultimate tensile strength, and elongation were 316 MPa, 332 MPa, and 11.8%, respectively, representing the best strength–ductility balance among the compositions examined. Increasing the Al₂Y content to 5 wt.% raised the elongation to 12.6% but reduced the strength because of particle agglomeration and microstructural coarsening. The variation in mechanical response is discussed in relation to recrystallized grain size, retained deformation, texture, and particle distribution. Within the processing window examined here, master-alloy addition offers a practical route for controlling Al₂Y reinforcement in Mg–Al–Ca–Mn composites.

Microstructures and mechanical properties of Mg-9Al/Ti metallurgical bonding prepared by liquid-solid diffusion couples were investigated. The results indicate that a metallurgical bonding was formed at the interface Mg-9Al/Ti, and the Mg₁₇Al₁₂ phase growth coarsening at the interfaces with the increase in heat treatment time. Push-out testing was used to investigate the shear strength of the Mg-9Al/Ti metallurgical bonding. It is shown that the shear strength presents an increasing tendency with the increased heat treatment time. The sequence is characterized, and the results show that the fracture takes place along the Mg-9Al matrix at the interface. The diffusion of Al and Ti elements play a dominant role in the interface reaction of Mg-9Al/Ti metallurgical bonding. By energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and thermodynamic analysis, it was found that Al₃Ti is the only intermetallic compound at the interface of Mg-9Al/Ti metallurgical bonding. These results clearly show that chemical interaction at the interface formation of Al₃Ti improves the mechanical properties of Mg-9Al/Ti metallurgical bonding.

A magnesium alloy containing Al₂Y particles was successfully fabricated by changing the content of Al in the Mg-6Y alloy melt. Its microstructure and mechanical properties were subsequently characterized. The results show that two types of Al₂Y particles were discovered in the Mg-6Y-xAl (x = 0.5–5) alloys, which are namely the polygonal particles in the pre-precipitated phase and the discontinuous network of particles in the eutectic phase. With an increase in Al content, the amount of pre-precipitated Al₂Y increases and the eutectic decreases gradually. When the Al content is 5 wt %, Al₂Y particles are almost all in the pre-precipitated phase in the Mg-6Y alloy. After hot extrusion, the YA65 alloy could be regarded as the Mg master alloy that contains Al₂Y particles with heterogeneous nucleation capability or Al₂Y particle-reinforced magnesium matrix composites. The tensile strength of the as-extruded magnesium alloy is significantly improved at ambient temperatures.