Relationships of strength to composition and phase constitution for three aged beta titanium alloys

X-ray diffraction techniques were used to study properties of three beta titanium alloys in the alpha aged condition. The alloys studied were Beta 111 (Ti-11.5 Mo-6 Zr-4.5 Sn), Beta C (Ti-3 Al-8 V-6 Cr-4 Mo-4 Zr), and 8-8-2-3 (Ti-8 V-8 Mo-2 Fe-3 Al). The volume percentage of alpha phase present and the lattice parameters of both the alpha and beta structures were determined for different ageing treatments. Ultimate tensile strength is related to both alpha content and beta unit cell size in these alloys. However, at high strength levels, beta unit cell size is a more sensitive indicator of tensile strength than percentage of alpha phase. The effects of precipitation hardening mechanisms and alloy partitioning on strengthening are discussed.