Apatite-Forming Ability Governing Bone-Bonding of Ti-15Zr-4Nb-4Ta Alloy Subjected to Calcium Solution Treatment
Ti-15Zr-4Nb-4Ta alloy is an attractive metal for orthopaedic implants, since it is free from cytotoxic elements and shows high mechanical strength. It was recently shown by an animal experiment  that this alloy tightly bonds to living bone, when it was subjected to 5 M NaOH solution and 100 mM CaCl2 solution treatments, heat treatment at 600 or 700 °C, and final water treatment at 80 °C. The bonding strength was increased markedly when the heat treatment temperature was increased from 600 to 700 °C. This increase of the bonding strength was attributed to the increase in apatite-forming ability of the treated alloy in a simulated body fluid (SBF)  with ion concentrations nearly equal to human blood plasma, although its reason was not revealed yet.
Eyup Sabri Kayali, Gultekin Goller and Ipek Akin
S. Yamaguchi et al., "Apatite-Forming Ability Governing Bone-Bonding of Ti-15Zr-4Nb-4Ta Alloy Subjected to Calcium Solution Treatment", Key Engineering Materials, Vols. 493-494, pp. 920-925, 2012