Enhancing wear resistance, anti-corrosion property and surface bioactivity of a beta-titanium alloy by adopting surface mechanical attrition treatment followed by phosphorus ion implantation

A two-step method of surface mechanical attrition treatment (SMAT) followed by phosphorous (P) ion- implantation was adopted to treat Ti-25Nb-3Mo-2Sn-3Zr (named as TLM) alloy. The initial SMAT process refined the grains from micrometer-scale to about 10-30 nm, and begot the TLM surface much rougher with apparently improved hydrophilicity. The subsequent P ion-implantation led to the formation of a hybrid structure of the TiP, beta-Ti nanograins and P-interstitial amorphous in the surface layer of the TLM alloy, and resulted in a slight decrease of the surface roughness and wettability of the SMAT-processed alloy. The indentation, tribology and potentiodynamic polarization tests indicated that the SMAT procedure concurrently enhanced the microhardness, wear-resisting property and corrosion resistance of the TLM alloy, and the followed P-ion implantation could further improve these tested properties. Moreover, the P-ion implanted TLM alloy was verified to exhibit much better surface bioactivity (including biomineralization in the simulated body fluid (SBF) and in-vitro cell adhesion) as compared to the original TLM alloy. With the remarkable improvements of the wear resistance and anti-corrosion property as well as the surface bioactivity of the P ion-implanted TLM alloy, our study provides an alternative avenue to fabricating new-type Ti-based orthopedic implants with superior comprehensive performance.