Abstract
Conventionally cast Mg-5Y-4Rare Earth-0.5Zr alloy (WE54) was solution treated (525 C/8 h - T4) and one part subsequently aged (200 oC/16 h - T6). Powder from the cast WE54 alloy prepared by gas atomizing was consolidated by extrusion at 250 oC or 400 oC.
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.