Strength and Fatigue Improvement of Metastable Beta Titanium Alloys by Boron Additions and Equal Channel Angular Extrusion Processing

Titanium alloys have been used as biomedical implant materials in total joint replacement procedures for many years. Recently, new metastable beta-type alloys based on Ti-Nb-Zr-Ta (TNZT) have been developed to address the shortcomings (e.g. incomplete biocompatibility, high elastic modulus, etc.) of the traditionally used materials. However, the tensile and fatigue properties of these alloys are too low for joint replacement implants in humans. In this investigation, boron additions and equal channel angular extrusion (ECAE) were used to produce grain refinement which can result in improved tensile, fatigue, wear, and forgeability characteristics of the TNZT alloys while maintaining their characteristically low elastic modulus value. The experimental results for the change in tensile, fatigue, wear, and forgeability properties are correlated with the ECAE induced microstructure to generate processing maps and quantitativel relations