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

Conventionally cast Mg–5Y–4Rare Earth–0.5Zr alloy (WE54) was solution treated (525 °C/8 h — T4) and one part subsequently aged (200 °C/16 h — 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 ~ 4–6 μm 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 (9 g/l NaCl/H2O) were monitored for 24 h. 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 (0.28 g in 28 ml of EMEM) of all 4 alloys were monitored by cinemicrography for 24 h. The MG-63 cells proliferate without cytotoxicity in all extracts.

► T6 treated WE54 alloy exhibit dense triangular arrangement of β″ and β′ phase prismatic plates.
► Microstructure of PM prepared WE54 alloy consists of α-Mg phase cells surrounded by β phase particles.
► PM produced WE54 corroded 10 times faster in physiological solution thanT4 and T6 treated WE54.
► MG63 cell spreading in EMEM extracts of PM prepared WE54 is comparable to that in control EMEM.
► Cell mitosis is enhanced in PM WE54 extracts compared to the control and extracts of T4 and T6 WE54.