Abstract
The serial-sectioning method has been used to determine the self-diffusion coefficients in b.c.c. γ-lanthanum and the solute diffusivities of lanthanum in b.c.c. S-cerium. The results are expressed by D La La = 1.3 × 10–2 exp (-24500/RT) cm2/sec and D Ce La = 3.8 × 10–2 exp (-24500/RT) cm2/sec. The similarity of the diffusion characteristics in the different rare-earth metals casts doubt on the validity of the activated interstitial model put forward in order to account for the peculiar diffusion behaviour in the b.c.c. phases of cerium and plutonium.