Résumé
The control of the oxygen level plays a key role to successful powder metallurgy of titanium alloys. Oxygen affects the mechanical properties of titanium alloys by decreasing the ductility. Thus, in this work the influence of oxygen content on the properties of Ti-6Al-7Nb, which is an attractive alloy due to its biocompatibility and mechanical properties required for load bearing medical implants, was investigated. Tensile and fatigue specimens were produced by metal injection moulding (MIM) using gas atomized Ti-6Al-7Nb powder. Various interstitial contents (O, N, C) were introduced into the specimens. Tensile and yield strength values increased by 12% when the oxygen equivalent increased from 0.15 to 0.34 wt.%. However, the ductility drastically deteriorated when 0.46 wt.% was reached. High cycle 4-point bending fatigue tests showed that interstitials have a negative impact on the dynamic properties of Ti-6Al-7Nb alloy. Microstructures and fracture surfaces were preliminary examined.