Secondary ion mass spectrometry was used to measure diffusion coefficients in single crystals of W. The diffusivity of Ta was equal to 8.82 x 10-15cm2/s at 2115K and to 1.62 x 10-13cm2/s at 2309K.

S.M.Klotsman, S.V.Osetrov, I.P.Polikarpova, G.N.Tatarinova, A.N.Timofeyev, O.P.Shepatkovskiy: Fizika Metallov i Metallovedenie, 1987, 64[1], 148-61. [Physics of Metals and Metallography, 1987, 64[1], 133-46])