title: Mechanical and electrochemical characterisation of new Ti-Mo-Nb-Zr alloys for biomedical applications.
abstract: The development and characterisation of new metallic biomaterials that contain non-toxic and non-allergic elements but possess low elastic modulus and low biodegradation rates, has become a topic of serious investigation in orthopaedic implant application. The lowering of elastic modulus and improving of corrosion resistance can be achieved by specific chemical alloying and super-elasticity effects, associated with a stress-induced phase transformation from the BCC metastable beta phase to the orthorhombic α″ martensite. Using this framework, this paper focuses on the effect of Nb and/or Zr micro-additions on the elastic modulus/yield strength balance and discusses microstructure, and the mechanical and electrochemical behaviour of four new β-Ti-8Mo-xNb-xZr (x=2-5) alloys, using tensile tests, X-ray diffraction, SEM characterisation, ultrasound technique and potentiodynamic polarisation methods. The results reveal that the alloys exhibit a pronounced microstructural sensitivity response, with alloying elements and excellent agreement between β-stability and high mechanical strength, with increasing Nb additions. Although all the alloys possess excellent corrosion resistance and low Young׳s modulus, Ti-8Mo-4Nb-2Zr alloy, which consists of β+α'' phases, exhibits a low Young modulus of 35GPa, which is lower than those of the commercial alloys already used in biomedical implantation. The significant corrosion resistance, nontoxicity and better mechanical compatibility are properties pertinent to preventing stress shielding and bone resorption in orthopaedic implant applications.
authors.affiliation: Department of Materials Science and Engineering, University of Sheffield, Mapping St, Sheffield S1 3JD, United Kingdom; Department of Metallurgical and Materials Engineering, University of Nigeria, post code 410001, Nsukka, Enugu state, Nigeria. Electronic address: paul.nnamchi@unn.edu.ng.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Nnamchi
authors.affiliation: Department of Metallurgical and Materials Engineering, University of Nigeria, post code 410001, Nsukka, Enugu state, Nigeria.
authors.forename: C S
authors.initials: CS
authors.lastname: Obayi
authors.affiliation: Department of Materials Science and Engineering, University of Sheffield, Mapping St, Sheffield S1 3JD, United Kingdom.
authors.forename: Iain
authors.initials: I
authors.lastname: Todd
authors.affiliation: Department of Materials Science and Engineering, University of Sheffield, Mapping St, Sheffield S1 3JD, United Kingdom.
authors.forename: M W
authors.initials: MW
authors.lastname: Rainforth
mesh_terms: D000497:Alloys / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D003343:Corrosion; D055119:Elastic Modulus; D008422:Materials Testing; D008982:Molybdenum; D009556:Niobium; D019736:Prostheses and Implants; D014025:Titanium; D015040:Zirconium
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D009556:Niobium; D008982:Molybdenum; D015040:Zirconium; D014025:Titanium
keywords: Biomedical application; Electrochemical characterisation; Metals and alloys; Non-toxic element; Titanium alloys; low elastic modulus