Search

Mg-Zn-Ca amorphous alloys are considered as potential bone implants. A large number of works have focused on the alloys under free corrosion environment. However, the real service environment of bone implants is a kind of chemistry-mechanics interactive environment in which the materials not only suffer corrosion by body fluids but also bear applied force induced by body movement. In order to imitate the real service environment, surface morphologies and mechanical properties of Mg-Zn-Ca amorphous alloys were studied under different chemistry-mechanics interactive environments in this paper. It was found that cracks and Ca/Mg phosphates formed on the surface of amorphous alloys. The compressive strength of the alloys decreased seriously but could still reach an acceptable value to avoid material failure. Fan-shaped patterns found on all the samples implied that brittle fracture was the main fracture form. Moreover, vein-like patterns could still be found in some areas, showing a locally plastic deformation. This was the reason why the alloy could maintain a high compressive strength after severe and interactive treatments. The study could guide related works in the establishment of experimental environments in the future, which will facilitate a more accurate biomedical evaluation of bone implants.

Mg-Zn-Ca metallic glass (MG) is effective for degrading azo dyes; however, the related surface evolution and degradation mechanisms are little known. We comparatively investigated the initial surface corrosion morphologies of melt-spun Mg66Zn30Ca4 MG in deionized water and artificial seawater. It was found that the basic corrosion behavior of the MG was the same, except that the corrosion process was accelerated in seawater. The presence of NaCl obviously promotes the formation of nano-ZnO on the surface of ribbons, causing the rapid degradation of azo dyes due to the photocatalytic effect. The degradation efficiency when combined with 3.5 wt % NaCl was over 100 times higher than that without NaCl. This indicates that Mg-Zn-Ca MG ribbons are effective additives for the degradation of azo dyes in seawater.

Rod samples of Mg60Zn35Ca5 bulk metallic glass composites (BMGCs) dispersed with Ti particles have been successfully fabricated via injection casting. The glass forming ability (GFA) and the mechanical properties of these Mg-based BMGCs have been systematically investigated as a function of the volume fraction (Vf) of Ti particles. The results showed that the compressive ductility increased with Vf. The mechanical performance of these BMGCs, with up to 5.4% compressive failure strain and 1187 MPa fracture strength at room temperature, can be obtained for the Mg-based BMGCs with 50 vol % Ti particles, suggesting that these dispersed Ti particles can absorb the energy of the crack propagations and can induce branches of the primary shear band into multiple secondary shear bands. It follows that further propagation of the shear band is blocked, enhancing the overall plasticity.