The role of heat treatment on the in vitro degradation and corrosion-initiated failure of the biodegradable Mg–Zn–RE alloy

Abstract

ABSTRACT In the current work, magnesium (Mg) alloy containing zinc (4%) and rare earth (RE) elements (1%) was produced by stir casting and the role of heat treatment on altering the microstructure, in vitro degradation and corrosion-initiated mechanical failure. Solutionising has introduced considerable grain refinement from 122 ± 6.9 μm to 95 ± 7.1 μm and decreased the amount of intermetallic. Potentiodynamic polarization tests indicated improved corrosion resistance for the solutionised alloy as indicated by with a lower corrosion current value (0.021 × 10-4 A.cm -2) compared with base alloy (0.027 × 10-3 A.cm -2) and annealed alloy (0.168 × 10-3 A.cm -2). In vitro degradation studies conducted in simulated body fluid solutions demonstrated better degradation resistance for the solutionised alloy compared with base and annealed alloy. Tensile tests conducted before and after exposing the samples to a corroding environment for 24 h showed the promising role of microstructure modification by solutionising on enhancing the resistance to corrosion-initiated failure with improved ductility compared with the base and annealed alloys. From the results it is concluded that solutionising can be successfully adopted to enhance the corrosion and mechanical properties of Mg-Zn-RE alloy for manufacturing of degradable implants for bone fixing applications.