Microstructures and Mechanical Behaviors of Ti-30Nb-1Fe-<i>x</i>Hf Alloys

Abstract

Effects of iron (1 mass%) and hafnium (1-7 mass%) on the microstructure and mechanical properties of Ti-30Nb base alloys were investigated in this study. Experimental results indicate that the addition of 1 mass% Fe to the Ti-30Nb alloy transforms the original þ þ ! structure into a single phase structure. Accompanying the structure change, both the tensile strength and 0.2% proof stress were reduced by some 15%, while the elastic modulus was reduced from 80 GPa to 68 GPa. Regarding the effect of Hf, precipitation of sporadic ! phase in the otherwise complete phase structure can be detected when hafnium is added. An addition of just 1 mass% Hf to the Ti-30Nb-1Fe alloy increases the tensile strength and 0.2% proof stress by 32% and 27%, respectively, while slightly decreasing the elastic modulus by some 10%. The Ti30Nb-1Fe-1Hf alloy has relatively high strength ($914 MPa T. S.), reasonable ductility ($10% El), and an elastic modulus of around 62 GPa. Consequently, the ratio of 0.2% proof stress to elastic modulus increases moderately. The ratio of 0.2% proof stress to elastic modulus of Ti30Nb-1Fe-1Hf was found to be 1:39 Â 10 À2 , which was around 1.8 times higher than Ti-6Al-4V (0:78 Â 10 À2 ), and around 3.5 times higher than c.p.Ti (0:4 Â 10 À2 ). Hafnium content exceeding 1 mass% gives no further improvement in the ratio of 0.2% proof stress to elastic modulus. From the results obtained here, Ti-30Nb-1Fe-1Hf alloy has excellent potential for orthopedic implant applications.

Effect of Nb addition on anodic behavior of Ti alloy in electrolyte containing calcium and phosphorus

“…In view of this, the present authors have developed a Ti-Nb-based alloy by adding Fe and Hf into a Ti-30Nb alloy to improve mechanical strength. This Ti-30Nb-1Fe-1Hf alloy has relatively high strength and low elastic modulus (UTS: 914 MPa, 0.2% proof stress: 862 MPa and E: 62 GPa) [2]. In addition, surface modification techniques, such as plasma treating [3], alkali treatment [4], sol-gel processes [5], plasma spray [6] and anodic oxidation [7], are generally applied to Ti implants to improve their biological performance.…”

Formation of an Antibacterial Oxide Film On Ti-Nb Alloy by Anodizing Oxidation

“…1 Nevertheless, for long-term implantation loosening of the prosthetic devices caused by "stress shielding effect" of the inserted implant on adjacent bone can occur 2 . To alleviate this effect, the present authors have developed the Ti-30Nb-1Fe-1Hf alloy with high strength and low elastic modulus (UTS: 914MPa, 0.2% Proof stress: 862MPa and E: 62GPa) 3 . The anodized Ti-30Nb-1Fe-1Hf alloy with an oxide film containing Ca and P was demonstrated to have good biocompatibility in our previous study 4 .…”

Effect of O<SUB>2</SUB>-Plasma Treatment on Surface Characteristics and Osteoblast-Like MG-63 Cells Response of Ti-30Nb-1Fe-1Hf Alloy

“…[8][9][10] In addition, Hf has been found to possess the advantage of enhancing strength, while at the same time reducing the elastic modulus of the Ti alloys. 11,12) In an authors' previous study, 13) a specific Ti-alloy, i.e., Ti-30Nb-1Fe-1Hf, had been developed, which exhibits relatively high strength and low modulus (UTS: 914 MPa, 0.2% Proof stress: 862 MPa, E: 62 GPa). In this study, Ti-30Nb-1Fe-1Hf alloy was used as the substrate material for evaluating the effect of surface treatment or modification on the surface characteristics and biocompatibility of this specific alloy.…”