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Bulk and porous metastable beta Ti-Nb-Zr(Ta) alloys for biomedical applications Brailovski, V.; Prokoshkin, S.; Gauthier, M.; Inaekyan, K.; Dubinskiy, S.; Petrzhik, M.; Filonov, M.Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca. In this work, metastable beta Ti-Nb-Zr(Ta) ingots were manufactured by vacuum arc melting. The ingots thus obtained were divided into two batches: the first subjected to cold rolling (CR) from 30 to 85% of thickness reduction and subsequent annealing in the 450 to 900°C temperature region, and the second atomized to produce 100 μm size powders. This powder was used to manufacture open-cell porous material. Regardless of the CR intensity, Ti-(18…20)Nb-(5…6)Zr (at.%) samples subjected to 600°C (1 h) annealing showed a significant material softening due to the stress-induced martensitic transformation. The Young's modulus of these alloys varied between 45 and 55 GPa, and the yield stress, between 300 and 500 MPa. The obtained Young's moduli, which are comparable to 55-66 GPa of concurrent beta-titanium alloys and 45-50 GPa of superelastic Ti-Ni alloys, come close to those of cortical bones. Compression testing of the porous material as a function of porosity (from~45 to 66%) and interconnected cell size (d 50 from 300 to 760 μm) showed the following properties: Young's modulus from 7.5 to 3.7 GPa, which comes close to that of trabecular bones, and ultimate compression strength, of from 225 to 70 MPa.

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Mechanical properties of porous metastable beta Ti-Nb-Zr alloys for biomedical applications Braïlovski, V.; Prokoshkin, S.; Gauthier, M.; Inaekyan, K.; Dubinskiy, S. melting. The obtained ingots were divided into two batches: the first subjected to cold rolling (CR) from 30 to 85% of thickness reduction, and subsequent annealing in the 450 to 600°C temperature range (1h). Regardless of the CR intensity, Ti-Nb-Zr samples subjected to 600°C annealing showed the highest fatigue resistance during roomtemperature cumulative cycling due to the stress-induced martensitic transformation occurring in the polygonized dislocation substructure (average subgrain size ∼ 100 nm). The second batch was atomized to produce 100-micronsize powders in order to manufacture open-cell porous material (cell size vary from 136 to 561 microns) of 46% porosity by means of powder metallurgy using a polymer-based foaming process. Tensile, compression and bending testing were performed at RT on foam samples annealed at 450 to 600°C (1h). Results indicated that Young's modulus of Ti-Nb-Zr foams significantly decreases as compared to the as-sintered material: when annealing temperature increases from 450 to 600°C, Young's modulus decreases from 10±2 GPa to 6±1 GPa. Under the same testing conditions, Ti-CP foams produced by the same technology and having similar porosity remain fairly insensible to post-sintering annealing.

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