Helium and argon diffusion in magnesium

The diffusion coefficients of He and A in Mg, obtained by measuring the rate of release of artificially introduced atoms from Mg sheet annealed at constant temperatures, are found to be: The coefficients (a) and (b) were obtained from Mg samples in which the He concentration was f He ∼ 1×10−6 and f He∼3–6×10−9 (atomic fraction) respectively and D 40A from samples in which fA∼2×10−5. Both D He and D A appeared to be concentration dependent. The isotope measurements require He and A diffusion by a mechanism involving vacancies; the vacancy or interstitialcy of the accepted mechanisms. There was no evidence of He or A gas bubble formation in Mg.