Author's School

School of Engineering & Applied Science

Author's Department/Program

Mechanical Engineering and Materials Science


English (en)

Date of Award

January 2010

Degree Type


Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Shankar Sastry


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 percent, but it is still well below the value of other prosthesis materials.


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