Alloy Design and Fabrication of Duplex Titanium-Based Alloys by Spark Plasma Sintering for Biomedical Implant Applications

Very often, pure Ti and (alpha + beta) Ti-6Al-4V alloys have been used commercially for implant applications, but ensuring their chemical, mechanical, and biological biocompatibility is always a serious concern for sustaining the long-term efficacy of implants. Therefore, there has always been a great quest to explore new biomedical alloying systems that can offer substantial beneficial effects in tailoring a balance between the mechanical properties and biocompatibility of implantable medical devices. With a view to the mechanical performance, this study focused on designing a Ti-15Zr-2Ta-xSn (where x = 4, 6, 8) alloying system with high strength and low Young's modulus prepared by a powder metallurgy method. The experimental results showed that mechanical alloying, followed by spark plasma sintering, produced a fully consolidated (alpha + beta) Ti-Zr-Ta-Sn-based alloy with a fine grain size and a relative density greater than 99%. Nevertheless, the shape, size, and distribution of a-phase precipitations were found to be sensitive to Sn contents. The addition of Sn also increased the alpha/beta transus temperature of the alloy. For example, as the Sn content was increased from 4 wt.% to 8 wt.%, the beta grains transformed into diverse morphological characteristics, namely, a thin-grain-boundary alpha phase (alpha(GB)), lamellar alpha colonies, and acicular alpha(s) precipitates and very low residual porosity during subsequent cooling after the spark plasma sintering procedure, which is consistent with the relative density results. Among the prepared alloys, Ti-15Zr-2Ta-85n exhibited the highest hardness (s340 HV), compressive yield strength (similar to 1056 MPa), and maximum compressive strength (similar to 1470). The formation of intriguing precipitate-matrix interfaces (alpha/beta) acting as dislocation barriers is proposed to be the main reason for the high strength of the Ti-15Zr-2Ta-85n alloy. Finally, based on mechanical and structural properties, it is envisaged that our developed alloys will be promising for indwelling implant applications.

Automated summary

A new alloy system with high strength and low modulus, Ti-15Zr-2Ta-xSn, was designed and prepared by mechanical alloying and spark plasma sintering. The addition of Sn improved the phase transformation temperature and morphology of the alloy. Among the prepared alloys, Ti-15Zr-2Ta-85n exhibited the highest mechanical properties, which can be attributed to the formation of precipitate-matrix interfaces acting as dislocation barriers.