Microstructural characteristics and mechanical properties of the hot extruded Mg-Zn-Y-Nd alloys

A new type of Mg-Zn-Y-Nd alloy for degradable orthopedic implants was developed. In the present study, the Zn and Y content was adjusted and their influences on the microstructures and mechanical behaviors were discussed in depth. The results showed that the as-extruded Mg-Zn-Y-Nd alloys are mainly composed of fine dynamic recrystallized grains (DRXed grains), large unDRXed grains and linearly distributed secondary phases. The change of Zn content exerts little influence on the grain structure of the extruded Mg-Zn-Y-Nd alloy, while the increase of Y content would hinder the dynamic recrystallization process and the growth of the DRXed grains, thus the size and volume fraction of the equiaxed DRXed grains decrease. The tensile and compressive properties are very little affected by Zn content because of the similar grain structure. As Y content increases, the tensile yield strength (TYS) and ultimate strength (TUS) increase while the elongation decreases, this is caused by a combined strengthening effect of grain refinement, texture, precipitation and twinning. The compressive yield strength (CYS) and ultimate strength (CUS) of Mg-Zn-Y-Nd alloy with different Y content exhibit a similar tendency as the tensile test. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.