Effect of extrusion temperature on mechanical properties and biological corrosion resistance of Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr alloy

The homogenized Mg-5.3Gd-2.6Y-1.1Nd-0.3Zr(mass fraction/%) ingots were extruded at different temperatures.The microstructures and mechanical properties of the solution-treated ingot and those extruded at different temperatures were investigated by optical microscopy(OM) and tensile test. The corrosion resistance of the alloys in Hank's solutions was evaluated by mass loss, hydrogen evolution and Tafel polarization tests. The surface corrosion morphology of the specimens after immersion was examined by scanning electron microscopy. The results show that the grains of the investigated alloy are refined substantially after extrusion, and their strength and ductility increase along with the decrease of the extrusion temperature, and the yield strength of the extruded alloy under 450℃ reaches 223.4MPa, which is about 60% higher than that of T4 alloy (139.8MPa). The extrusion deformation also has positive effects on the alloys' corrosion resistance, and corrosion resistance of the alloy increases first and then decreases along with the decrease of the extrusion temperature. The one extruded under 450℃ seems to show the best corrosion resistance,whose corrosion rate is 0.74mm/a.