In this study, Mg-8Sn-2Zn-2Al (TZA822) alloys with varying Mg₂Sn contents prior to extrusion were obtained by different pre-treatments (without and with T4), and the strengthening response related to micro and nano-size Mg₂Sn precipitates in the extruded TZA822 alloys was reported. The results showed that the morphology of nano-size Mg₂Sn precipitates exhibits a significant change in basal plane from rod-like to spherical, owing to the decrement in the fraction of micro-size particles before extrusion. Meanwhile, the spherical Mg₂Sn precipitates provided a much stronger strengthening effect than did the rod-like ones, which was ascribed to uniform dispersion and refinement of spherical precipitates to effectively hinder basal dislocation slip. As a consequence, the extruded TZA822 alloy with T4 showed a higher tensile yield strength (TYS) of 245 MPa, ultimate tensile strength (UTS) of 320 MPa and elongation (EL) of 26.5%, as well as a lower degree of yield asymmetry than their counterpart without T4. Detailed reasons for the strengthening effect were given and analyzed.

Biodegradable Mg–Zn–Ca-based metallic glasses (MGs) present improved strength and superior corrosion resistance, compared to crystalline Mg. In particular, in vivo and in vitro attempts reveal that biodegradable Mg–Zn–Ca-based MGs possess excellent biocompatibility, suggesting that they are ideal candidates for temporary implant materials. However, the limited size and severe brittleness prevent their widespread commercialization. In this review, we firstly summarize the microstructure characteristic and mechanical properties of Mg–Zn–Ca-based MGs. Then, we provide a comprehensive and systematic understanding of the recent progress of the biocorrosion and biocompatibility of Mg–Zn–Ca-based MGs. Last, but not least, the outlook towards the fabrication routes, composition design, structure design, and reinforcement approaches of Mg–Zn–Ca-based MGs are briefly proposed.