Grain boundary segregation (GBS) of solutes influences the grain size, texture, and strength of Mg wrought alloys. So far, solutes’ GBS in Mg has mostly been investigated by qualitative experimental observations. In this work, we develop a quantitative model to compute the grain boundary segregation energy (ΔE_seg) in binary Mg based alloys that takes the relative atomic density of GB into account. The model is utilized to compute ΔE_seg of Al, Zn, Ca, Sn, Y, Gd, and Nd solutes in Mg. The result suggests that rare earth elements and Ca are more prone to GBS than Al, Zn, and Sn. Segregation of Gd solutes can explain the smaller grain size and slower grain growth in Mg-Gd extruded alloys than Mg-Al and Mg-Zn counterparts. It also provides an explanation for the weak extrusion texture in Mg-Gd.

Molecule hydrogen (H₂) has been used to suppress tumor growth. To employ the H₂ therapy, it is necessary to use a proper agent for continuous generation of H₂. As a biodegradable metal, magnesium (Mg) generates H₂ in an aqueous environment, but the H₂ release rate is still too low. Here, we design a Mg-Al-Ca (AX) alloy that degrades very rapidly due to the presence of a secondary phase Al₂Ca. Having a reduction potential much higher than Mg and any other Mg-based secondary phases, Al₂Ca accelerates the corrosion of the Mg matrix by a micro-galvanic process. Al₂Ca also enhances the strength and ductility of the AX alloy. AX alloy rods show better anti-tumor efficacy than pure Mg rods in vivo. Moreover, implanted AX alloy rods can be heated under an alternating magnetic field to suppress large-size tumors. This work suggests that the H₂ therapy using highly degradable Mg alloys may provide an effective cancer treatment.

The mechanical properties of Mg–Al–Ca alloys are significantly affected by their Laves phases, including the Al₂Ca phase. Laves phases are generally considered to be brittle and have a detrimental effect on the ductility of Mg. Recently, the Al₂Ca phase was shown to undergo plastic deformation in a dilute Mg-Al-Ca alloy to increase the ductility and work hardening of the alloy. In the present study, we investigated the extent to which the deformation of Al₂Ca is driven by dislocations in the Mg matrix by simulating the interactions between the basal edge dislocations and Al₂Ca particles. In particular, the effects of the interparticle spacing, particle orientation, and particle size were considered. Shearing of small particles and dislocation cross-slips near large particles were observed. Both events contribute to strengthening, and accommodate to plasticity. The shear resistance of the dislocation to bypass the particles increased as the particle size increased. The critical resolved shear stress (CRSS) for activating dislocations and stacking faults was easier to reach for small Al₂Ca particles owing to the higher local shear stress, which is consistent with the experimental observations. Overall, this work elucidates the driving force for Al₂Ca particles in Mg–Al–Ca alloys to undergo plastic deformation.

Mg-Y cast alloy shows excellent ductility (elongation to failure> 15%) compared with pure Mg and commercial Mg cast alloys. By monitoring the microstructure evolution during an in situ tensile test of a Mg-2.5 wt%Y alloy, we identify the activation of prismatic <c> slip, which is rare in Mg. Synchrotron X-ray micro-beam Laue diffraction (μ-Laue) and transmission electron microscopy revealed the morphology of prismatic <c> slip bands and individual <c> dislocations. Density functional theory and molecular dynamics calculations indicate that solute Y can significantly reduce the stacking fault energy (SFE) along <c> direction on prismatic plane in Mg lattice and thus facilitate the nucleation of <c> dislocations during deformation. The presence of free <c> dislocations in the Mg lattice can also lead to nucleation of {10–12} twins even under unfavorable geometric conditions.