Microstructure, corrosion resistance and cytocompatibility of Mg–5Y–4Rare Earth–0.5Zr (WE54) alloy

Abstract

Conventionally cast Mg–5Y–4Rare Earth–0.5Zr alloy (WE54) was solution treated (525°C/8h — T4) and one part subsequently aged (200°C/16h — T6). Powder from the cast WE54 alloy prepared by gas atomizing was consolidated by extrusion at 250°C or 400°C. Dense triangular arrangement of prismatic plates of transient D019 and C-base centered orthorhombic phases precipitated in the α-Mg matrix during the T6 treatment. Both alloys prepared by powder metallurgy exhibit similar microstructure consisting of ~4–6μm α-Mg matrix fibers surrounded by particles of the equilibrium Mg5(Y, Nd) phase and of oxides. Open circuit potential and polarization resistance in the isotonic saline (9g/l NaCl/H2O) were monitored for 24h. The corrosion rate of the T4 and T6 treated alloys was about 80 times lower than that of commercial Mg. Both alloys prepared by powder metallurgy exhibited approximately 8 times higher corrosion resistance than commercial Mg. The human MG-63 osteoblast-like cells spreading and division in the extracts (0.28g in 28ml of EMEM) of all 4 alloys were monitored by cinemicrography for 24h. The MG-63 cells proliferate without cytotoxicity in all extracts.