Extraordinary high strength Ti-Zr-Ta alloys through nanoscaled, dual-cubic spinodal reinforcement.
While titanium alloys represent the current state-of-the-art for orthopedic biomaterials, concerns still remain over their modulus. Circumventing this via increased porosity requires high elastic admissible strains, yet also limits traditional thermomechanical strengthening techniques. To this end, a novel β-type Ti-Zr-Ta alloy system, comprised of Ti-45Zr-10Ta, Ti-40Zr-14Ta, Ti-35Zr-18Ta and Ti-30Zr-22Ta, was designed and characterized mechanically and microstructurally. As-cast, this system displayed extremely high yield strengths and elastic admissible strains, up to 1.4GPa and potentially 1.48%, respectively. This strength was attributed to a nanoscaled, cuboidal structure of semi-coherent, dual body-centered cubic (BCC) phases, arising from the thermodynamics of interaction between Ta and Zr; this morphology occurring with dual BCC-phases is heretofore unreported in Ti-based alloys. Further, cell proliferation investigated by MTS assay suggests this was achieved without sacrificing biocompatibility, with no significant difference to either empty-well or commercially-pure Ti controls noted.



The current research details microstructural, mechanical, and biological investigations into four novel biomedical alloys in a hitherto uninvestigated region of the Ti-Zr-Ta alloy system; Ti-45Zr-10Ta, Ti-40Zr-14Ta, Ti-35Zr-18Ta and Ti-30Zr-22Ta. We find that the investigated alloys display 0.2% yield strengths of up to 1.40GPa and elastic admissible strains of up to 1.48%, along with biological properties comparable to that seen in the conventional metallic biomaterial ASTM Grade-2 CP-Ti, achieved in the complete absence of traditional thermomechanical processing techniques. This is attributed to the presence of a dual-BCC cuboidal nanostructure, achieved via spinodal decomposition; while similar structures have been reported in e.g. Ni-based superalloys, we believe this is the first such structure investigated in a Ti-based material. As such, this work is felt to be of great interest in aiding the design and manufacture of highly-biocompatible, porous, metallic biomaterials for orthopedic application.
School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia; Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia.
Arne
A
Biesiekierski
National Institute for Materials Science, Tsukuba 305-0047, Japan.
Dehai
D
Ping
School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia.
Yuncang
Y
Li
College of Materials Science and Engineering, Jilin University, Changchun, Jilin 130025, China.
Jixing
J
Lin
School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia.
Khurram S
KS
Munir
National Institute for Materials Science, Tsukuba 305-0047, Japan.
Yoko
Y
Yamabe-Mitarai
School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia; Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia. Electronic address: cuie.wen@rmit.edu.au.
Cuie
C
Wen
D000497:Alloys / Q000737:chemistry; D001672:Biocompatible Materials / Q000138:chemical synthesis*; D019245:Compressive Strength; D055119:Elastic Modulus; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D013314:Stress, Mechanical; D013635:Tantalum / Q000737:chemistry*; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
D000497:Alloys; D001672:Biocompatible Materials; D013635:Tantalum; D015040:Zirconium; D014025:Titanium
Biomedical; Nano-structure; Spinodal decomposition; Titanium alloy; Transmission electron microscopy (TEM)