Micro-galvanic corrosion behavior and mechanical properties of extruded Mg–2Y–1Zn-0.4Zr-0.3Sr alloys with different extrusion temperament immersed in simulated body fluids

Abstract The Mg–2Y–1Zn-0.4Zr-0.3Sr alloy is a new kind of degradable material for biomedical application. In order to optimize its corrosion resistance and mechanical properties, the plastic extrusion deformation was implemented to improve its properties. The results indicated that the alloy's grains were refined significantly due to dynamic recrystallization (DRX), and the W-phase (Mg3Zn3Y2) was crashed into particles distributed along extrusion direction; meanwhile, the elongated un-complete dynamic recrystallization (un-DRX) grains decreased with the increase of extrusion temperature. The micro-galvanic corrosion cell was easily formed between the W-phase (2.9 V) and the Mg matrix (2.2 V) due to the large potential difference, the corrosion tendency, however, of micro-galvanic was weakened owing to the part of W-phase dissolved into Mg matrix with the temperature enhancement. In addition, the grain boundary, potential higher than adjacent grains, also acted as a barrier role to prevent the spread of corrosion and improve the corrosion resistance. In a nutshell, the extruded Mg–2Y–1Zn-0.4Zr-0.3Sr alloy at 400 °C (UTS = 254Mpa, YS = 195Mpa, EL = 27% and CR = 0.47 ± 0.099 mm/y) meet the basic requirements as biomedical implant materials.