Journalpaper

Development of Ti-22Nb-xZr Using Metal Injection Moulding for Biomedical Applications

Abstract

Research on biomaterials is connected inherently with the various aspects of materials science, chemistry, biology and medicine. Frequently used biomaterials for implants are titanium alloys because of their high corrosion resistance and biocompatible behaviour together with high strength and low density. One main characteristic property for the consideration of a potential implant material is the Young’s modulus which should correspond to that of human bone (4~30 GPa) as close as possible. β-Ti alloys exhibit currently the lowest value of typically 60 to 80GPa. β-Ti phase is stabilized with additive elements such as Mo, Ta, Hf and Nb. In particular, Ti-Nb alloys can exhibit a Young’s modulus around 50 to 60 GPa. Metal Injection Moulding (MIM) is a promising production technology because it overcomes the productivity and shape limitations of traditional powder compaction methods. However, formation of carbide precipitates at the grain boundaries deteriorating the ductile behavior of the materialhas become a challenge in MIM. Recent research using MIM on Ti-22Nb with the addition of Zr has revealed the reduction of carbide precipitates. In this study, different amounts of zirconium were added varying between 2 to 10 wt%. Samples produced with 10% Zr revealed the highest tensile strength of 840 MPa. In addition, specimens with higher zirconium content showed the highest ductility. XRD measurements revealed an increase in lattice constant effecting an increase of the carbon solubility of the Ti-matrix and, thus, a reduction of the carbide precipitation.
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