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Recently, Mg and its alloys have attracted much attention because of their excellent biocompatibility and biodegradability. High anisotropy of Mg crystal structure, however, limits the movement of some slip systems; therefore, pure magnesium possesses poor ductility and/or toughness. A number of studies have revealed that alloying with solute elements and modification of grain structure improved these drawbacks. In this study, to clarify the effect of adding solute elements, e.g., calcium and zinc, impact toughness testing and first-principles calculations of generalized stacking fault energy and grain boundary cohesive energy were conducted. For example, alloying magnesium with calcium and zinc and controlling the microstructure produced a Mg alloy with a high compressive fracture strain of 0.40, which was greater than the estimated maximum strain for fastening a surgical clip. This high fracture strain arose from the enhanced grain boundary cohesive energy and reduced anisotropy of slip systems by solute segregation. As a result, the alloy successfully occluded blood vessels.
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- Material Design for Enhancing Toughness of Mg Alloy and Application for Biodegradable Devices
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