Effect of microstructural and texture evolution of ECAP-processed Mg-Zn-Zr alloy on the corrosion and wear behaviours for bone repair applications

Abstract

Mg-Zn-Zr alloys show great potential for replacing the currently used materials in biodegradable applications. They exhibit similar mechanical properties to that of human bones, while possessing favorable biodegradable properties that can be engineered to allow the complete, safe degradation of the alloy in the human body around the time the bones fully heal, without the need for a removal surgery. Literature confirms that grain refinement through processing via severe plastic deformation (SPD) techniques enhances both corrosion and wear behavior of Mg alloys; thus, in this study Mg-3Zn-0.6 Zr (ZK30) billets were ECAP-processed for up to 4-passes of route Bc to investigate their wear and corrosion behaviors improvement in relation to their microstructural and texture evolutions. Electron back-scatter diffraction (EBSD) was used to study microstructural and texture evolution of the billets, their electrochemical behavior was investigated using a body simulated fluid as a corrosive agent, and wear tests with load, velocity and distance parameters were carried out to investigate the improvements resulting from the produced ultrafine-grained structure and crystallographic texture. EBSD revealed that 4-pass ECAP processing yielded a grain size reduction of 92.7%. Accordingly, this ultrafine-grained structure reduced the corrosion rate by 94%, improved the corrosion resistance by 726%, and notably improved the billets’ wear behavior, compared to the as-annealed condition. Therefore, this in-depth analysis confirms the promising potential of ZK30 alloy for industrial use in bone applications.