Powder metallurgy processing of Nb-modified near β titanium alloys prepared with elemental powders

Near β Ti alloys typically show high specific strength and provide a wide spectrum of mechanical properties with different heat treatments. In this work, a commercial near β Ti alloy Ti-5553 (Ti-5Al-5V-5Mo-3Cr-0.5Fe) was prepared through powder metallurgy using the blended elemental powder approach. Additionally, alloy modifications with 6 wt.% Nb (Ti-6Nb-5Al-2.5V-5Mo-3Cr-0.5Fe) and 12 wt.% Nb (Ti-12Nb-5Al-5Mo-3Cr-0.5Fe) were investigated. Specimens were prepared by uniaxial cold compaction of blended powders at room temperature with sintering conducted at 1300°C for 2 h under Ar atmosphere. Microstructure investigation revealed reasonable homogenisation of alloying elements and colony sizes in the order of 80-100 μm with porosity below 10%. Moreover, the bending strength of as-sintered Ti-12Nb-5Al-5Mo-3Cr-0.5Fe was about 850 MPa and the micro-Vickers hardness was approximately 370 HV. The alloy modifications with Nb increased strength without loss in flexural strain.