Investigation of the process-dependent microstructure and mechanical properties of E-PBF processed Ti-27Nb-6Ta with low Young’s modulus based on pre-alloyed powders

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The use of structural implants in the human body becomes necessary in the event of loss or restoration of lost skeletal functionality that can occur due to tumors, deformities, fractures, infections and osteolysis. Most of the implant materials used are pure metals or metallic alloys. Titanium and its alloys, in particular Ti-6Al-4V, are used most frequently. Implants made of forged or additively manufactured Ti-6Al-4V are characterized by very good strength and good biocompatibility, the latter being promoted by a native oxidation layer on the metal surface. Due to its good osseointegration, Ti-6Al-4V is currently used for application in craniofacial, orthodontic and orthopedic implants. However, recent results indicate that aluminum and vanadium can be the cause of peripheral neuropathy, osteomalacia, and Alzheimer's disease. The elastic properties of Ti-6Al-4V also have a very disadvantageous effect. Ti-6Al-4V has a Young’ modulus of 110 GPa, thus, being 4 to 7 times stiffer than a human bone. This can ultimately cause the “stress shielding” effect. Additive manufacturing allows a comparatively inexpensive realization of individual implants specially adapted to the patient. In addition, structural details can be introduced that enable the implant to be designed in accordance with the actual load. This project comprises additive manufacturing of structures made of Ti-27Nb-6Ta by means of electron beam melting (PBF-EB/M), as well as the characterization of process, microstructure and geometry-dependent mechanical parameters taking into account the powder used for production (evaluation of the quality of the powder in three defined conditions). The Ti-Nb-Ta alloy envisaged for the investigations generally has sufficiently high strength values as well as a Young’s modulus being reduced by approx. 45% as compared with Ti-6Al-4V. Even if preliminary findings are available for samples manufactured by means of laser melting, no statements regarding additive manufacturing strategies being characterized by highest resource efficiency can be made. Questions about the influences of powder condition on the component properties upon PBF-EB/M will close prevailing knowledge gaps. The special process conditions for PBF-EB/M, i.e. the high process temperatures and processing in a vacuum, are of highest interest here.