Remarkably enhancing mechanical and degradation performance of cast MgZn1.2 alloys via small amount addition of zirconium combined with hot extrusion for orthopedic applications

Abstract

The MgZn1.2Zr0.35 (wt%) alloys for orthopedic applications enhanced by small amount addition of zirconium and subsequent hot extrusion working based on cast MgZn1.2 system were successfully fabricated. As 0.35% zirconium (Zr) added, the mean grain sizes of as-cast MgZn1.2 alloys were found to decrease from 107 μm to 72 μm attributed to the Zr element dissolved into alloys and undissolved Zr contents providing nucleation sites which could effectively inhibit grain growth. The using of hot extrusion further significantly refined grain structure to 10 μm because there were dynamic recrystallization (DRX) behaviors. Simultaneously broken second phases particles play a role in inhibiting recrystallized grains’ growth. The yield strength (YS), ultimate tensile strength (UTS) and bending strength (BS) remarkably increase from 30 MPa to 194 MPa, 130 MPa–238 MPa and 275 MPa–496 MPa respectively without sacrificing elongation at a high level of 19%. Furthermore, MgZn1.2Zr0.35 system after hot extrusion exhibits the least degradation current density of 7.529 × 10−5 A in simulated body fluid (SBF) reduced an order of magnitude compared with 9.863 × 10−4 A of cast MgZn1.2 alloys result from that adding zirconium combined with hot extrusion effectively enhances degradation resistance attributed to the increase consistency of protective film on magnesium by means of grain refinement.

Keywords

• Mg-Zn-Zr alloy
• Biodegradable implant
• Microstructure refinement
• Mechanical properties
• Degradation resistance
• Anti-Corrosion mechanism