| New metastable-beta type titanium alloys based on the biocompatible elements Ti-Nb-Zr-Ta (TNZT) have been developed to address the shortcomings (e.g. incomplete biocompatibility, high modulus, etc.) of the traditionally used materials in joint replacement prostheses. Equal channel angular extrusion (ECAE) processing has the capability to improve the mechanical properties of these alloys to broaden their potential biomedical applications. The focus of this investigation is to evaluate and optimize the ECAE process to produce maximum property improvement, and explore the effectiveness of boron as a grain refining agent. Deformation mechanisms are identified for various processing conditions, and the strain distribution induced during extrusion is examined using finite element techniques. Multi-pass ECAE processed samples were examined using optical and transmission electron microscopy, and subjected to tensile, fatigue, and wear testing. It was found that ECAE has a beneficial impact on all of the properties tested. The modulus value was increased by approximately 25%, but it is still well below the value of other prosthesis materials. |
