ISOTOPE EFFECT IN INTERMETALLIC DIFFUSION

Journal Article · Wed Mar 15 00:00:00 EST 1961 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.121.1649· OSTI ID:4058308

Mullen, J G

Ten measurements of the isotope effict for diffusion of Fe/sup 55/ and Fe/sup 59/ in pure single cryatals of silver and copper were made over approximately a 300 deg C temperature interval below the melting point. The measured isotope effect was found to be about 2/3, significantly less than the value of unity expected from conventional reaction rate theory. It is shown from Vineyard's extension of reaction rate theory that the measured isotope effect is to a good approximation a product of the Bardeen-Herring correlation factor and the fraction of the total translational kinetic energy associated with the diffusing tracer in a tracervacancy exchange. It is shown that the ring, interstitialcy, crowdion, and relaxion mechanisms are not responsible for diffusion in the systems studied. The three-frequency theory of correlation for vacancy diffusion in fcc lattices is extended to show that the relative frequency factors are vacancy exchange. It is shown that the ring, interstitialcy, crowdion, and relaxion mechanisms are not responsible for diffusion in the systems studied. The three-frequency completely specified by a knowledge of the correlation factor and the diffusion coefficients. An expression for the difference in the Arrhenius Q and the activation energy due to the temperature dependence of the correlation factor is derived. This theory is shown to be inconsistent with the observed isotope effect if many-body effects are neglected. It is shown that a "long-range" repulsive interaction between the vacancy and impurity would be necessary if the measured isotope effect is to be explained purely in terms of correlation. (auth)

• Research Organization: Univ. of Illinois, Urbana
• NSA Number: NSA-15-014783
• OSTI ID: 4058308
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Vol. Vol: 121; Other Information: Orig. Receipt Date: 31-DEC-61
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

METALS, CERAMICS, AND OTHER MATERIALS
COPPER
CRYSTALS
DEFECTS
DIFFUSION
EXCITATION
FREQUENCY
IMPURITIES
IRON 55
IRON 59
ISOTOPE EFFECTS
LATTICES
MEASURED VALUES
MELTING POINTS
REACTION KINETICS
SILVER
TEMPERATURE