Diffusion coefficient of ⁵¹Cr in single crystal α-titanium has been measured over the temperature range from 875 to 1123 K. The diffusion coefficient of ⁵¹Cr in α-Ti is about two orders of magnitude larger than the self-diffusion coefficient in α-Ti. The temperature dependence of diffusion coefficient of ⁵¹Cr in α-Ti parallel and perpendicular to the c-axis is, respectively, expressed as
D_⁄⁄=(2.2_−1.4^+0.8)×10⁻⁶exp(−165.5±4.1kJ·mol⁻¹⁄RT)m²s⁻¹,
D_⊥=(2.2_−0.5^+0.4)×10⁻⁶exp(−169.4±2.1kJ·mol⁻¹⁄RT)m²s⁻¹.
The diffusivity of Cr in α-Ti parallel to the c-axis is larger than that perpendicular to the axis. Diffusion of Cr in polycrystalline α-Ti alloys: Ti-4.4Al, Ti-2.4Sn and Ti-3.7Al-2.5Sn (mass%), has also been investigated. The addition of Al suppresses the diffusion of Cr, while Sn hardly affects the diffusion.