Accession Number:

AD0266332

Title:

THEORY OF VACANCY MECHANISM ORDER-DISORDER KINETICS

Descriptive Note:

Scientific note,

Corporate Author:

TECHNION - ISRAEL INST OF TECH HAIFA

Personal Author(s):

Report Date:

1961-05-01

Pagination or Media Count:

18.0

Abstract:

T OR R- I OR R KI TIC OF T RUC UR C UZ C U U AND Fe3Al is considered in terms of a vacancy mechanis . The unit ordering process is required to b consistent with the macroscopic definition of a change in long-range order and is thus ta interchange mechanism is obtained. The rate cons ants are evaluated by assuming the zeroth order quasi-chemical approximation. Particular attention is given to the Fe3Al structure because of its uniqueness in exhibiting an ordering of second neighbors and its not being considered by prev ake to be a simul n ou umpi g of a A atom into an alpha site and a B atom into a beta site. A rate equation formally similar to those obtained by Dienes and by Vineyard for the direct interchange mechanism is obtained. The rate cons ants are evaluated by assuming the zeroth order quasi-chemical approximation. Particular attention is given to the Fe3Al structure because of its uniqueness in exhibiting an ordering of second neighbors and its not being considered by previous treatments. T HE ANALYSIS OF ORDER-DISORDER KINETICS DATA TO OBTAIN ACTIVATION ENERGIES OF VACANCY FORMATION AND MIGRATION IS CONSIDERED IN THE LIGHT OF THE PRESENT RESULTS. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE