Computer simulation of radiation damage in iron aluminide
"A computer program, designed to simulate the ordered state of the B.C.C. alloy, Fe₃Al, was used to study the effects of irradiation on an order-disorder alloy. Twenty-six runs were made with this program representing a variety of initial conditions. In all cases, the final damaged state consisted of Frenkel defects, vacancy-interstitial pairs; and the distance separating these pairs was a sensitive function of the energy and direction imparted to the primary knock-on. Both the vacancy and the interstitial were found to be normal, stable defects, with the interstitial residing in a "split"-configuration oriented in the  direction. The threshold energies for permanent atomic displacement were also found to be strongly directionally dependent. The  direction proved to have the lowest threshold with a value of 22 eV (for a chain of all Fe atoms) for the directions studied. The threshold for the  direction was about 44 eV, while that for the  direction was not determined because of its very complex behavior. "Replacement chains" were prevalent in the  and the  directions. After an initial energy loss of about 10 to 15 eV, the replacement chains progressed with relatively little loss of energy per atomic collision. "Focusons" were also prevalent and served as the primary mechanism for dissipating energy from the collision chain. This mechanism was operative in the  and [lll] directions and was especially noticeable during the "defocusing" collisions. The defocusing replacement chains were introduced at energies of about 110 eV and knock-on directions from 1 to 1.5' away from the  and  directions. The energy dissipation along a defocused chain closely resembled the "thermal spike" concept; while, the extensive expansion of the lattice near the end of the defocused chain (especially in the  direction) was reminiscent of a "plasticity spike." The presence of aluminum atoms had a strong influence on several of the dynamic events. The small mass of the aluminum atoms present in the [lll] chain impeded the progress of the replacement chain; while, the defocusing in the  and  directions was enhanced by the aluminum's low mass and high mobility. Disordering was found to be most significant in the defocused chains. The  and  replacement chains containing all iron atoms showed no disordering when the iron atoms exchanged places. Since the aluminum atoms were not replaced in either the  direction or the  (alternate iron and aluminum atoms) direction, no disordering occurred. The disordering in the defocused chains arose from the general mixing of the lattice atoms along the chain especially in the "plasticity spike" region"--Abstract, page ii-iv.
Leighly, Hollis P., 1923-2004
Edwards, D. R.
Hill, Otto H.
Mining and Nuclear Engineering
M.S. in Nuclear Engineering
University of Missouri at Rolla
ix, 106 pages
© 1968 Roland Otto Jackson, All rights reserved.
Thesis - Open Access
Library of Congress Subject Headings
Iron-aluminum alloys -- Effect of radiation on
Order-disorder in alloys
Radiation -- Simulation methods
Print OCLC #
Electronic OCLC #
Link to Catalog Recordhttp://laurel.lso.missouri.edu/record=b1067688~S5
Jackson, Roland Otto, "Computer simulation of radiation damage in Fe₃Al" (1968). Masters Theses. 5251.