The Effect of Zirconium on Internal Friction in Columbium

The effect of zirconium on internal friction in columbium was investigated over the frequency range of 0.5 to 10 cps. An entirely new peak was observed which was attributed to the diffusion of oxygen in the vicinity of zirconium atoms. The normal columbium oxygen peak was not observed until approximately 0.14 wt% oxygen was added to the specimens. The normal columbium-nitrogen peak was readily observed, but a zirconium-nitrogen peak was not observed until oxygen concentration was reduced below 0.1 wt%. These observations are explained on the basis of a strong attraction between zirconium and oxygen atoms. As a preliminary to this investigation, the diffusivity of zirconium in columbium at 1930°C was determined. A value for D0 and the activation energy were calculated so that the diffusivity at any temperature could be obtained from the expressionD=0.57 exp 87 000/RT.