Influence of heat treatment on the mechanical properties, corrosion behavior, and biocompatibility of Zr56Al16Co28 bulk metallic glass

This paper reports the influence of heat treatment on the mechanical properties, corrosion behavior and biocompatibility of Zr56Al16Co28 bulk metallic glass (BMG) investigated by dynamic mechanical analysis (DMA), electrochemical analysis in vitro hemocompatibility and in vivo experiments. Zr56Al16Co28 alloys with amorphous, semi-crystalline and fully crystallized microstructures were obtained by thermal treatment of as-cast Zr56Al16Co28 BMG below or above glass transition temperature (Tg). The modulus slightly decreased with increasing temperature below Tg whereas the modulus dramatically increased treated above Tg due to the appearance of crystalline phase. The passivation potential did not change for samples heat-treated below Tg but decreased significantly above Tg, which indicated that Zr56Al16Co28 BMG possessed better corrosion resistance than crystallized Zr56Al16Co28 alloys. Zr56Al16Co28 alloys showed good hemolytic resistance regardless of the microstructural condition and presented lower hemolytic rate than their crystallized counterparts. In vivo test revealed that as-cast Zr56Al16Co28 BMG presented similar biocompatibility to the structurally relaxed BMG and better biocompatibility than the crystallized counterparts. Mice implanted with Zr56Al16Co28 BMGs showed lower degree of inflammatory infiltration response compared to mice implanted with the crystallized counterparts. The results showed that the properties of as-cast Zr56Al16Co28 BMG were generally comparable to its structurally relaxed counterpart and superior to the crystalline samples.