Abstract:
The aim of this study was development of Mg-Zn-Nd-Y alloy for biomedical applications and to identify the effect of yttrium (Y) addition on the phase development and mechanical and corrosion behavior of the alloys in as-cast, rolled, and extruded conditions. The result showed that Mg-2Zn-1Nd alloy consists of α-Mg, Mg41Nd5, and some eutectic phases. The addition of a small amount (0.5 wt.%) of Y in the alloy led to the formation of the icosahedral quasi-crystalline I (Mg3YZn6) phase, and further addition of Y (1.0wt%) led to the formation of W-phase (Mg3Y2Zn3). The Y addition significantly refined grains in the extruded state with the grain size of 17μm when Y content is 1%. The precipitates were more fragmented in extrusion than in the rolling state. The secondary dendritic arm spacing was more refined in the as-cast state as a function of Y addition. The presence of the I-phase in the alloy with 0.5wt% Y increased hardness than the alloy containing 1wt% Y due to the formation of the W phase. The maximum hardness achieved is 78.15Hv in extruded state when the Y content is 0.5%. the refined grain structures with higher volume fraction of grain boundaries, act as barriers to dislocation motion increasing the material's hardness in extruded sample than the rolled one. The weight loss corrosion was performed for the corrosion rate calculation and the alloy with the I phase had the lowest corrosion rate, whereas the W phase containing alloy showed a moderate corrosion rate, and the alloy without Y content had the most corrosion rate. The extruded state exhibited the best corrosion resistance with the corrosion rate of 0.392mm/a when Y is 0.5% than the rolled and the as-cast state due to more grain refinement, and fragmentation of the second phases. The corrosion electrochemistry also ensured the corrosion resistance behavior of the extruded alloy.