The energetic characteristics of self and impurity interstitial A1 atom migration in unstressed a-Fe and in stress gradients are studied by a computer simulation method. The stress gradient effect displays itself in the fact that the energetic barriers against interstitial migration along the stress gradient are lower than those opposite to it. The migration energy of the A1 atom of an Fe-A1 dumbbell is considerably lower than that of the Fe atom in the same dumbbell; it means that A1 atoms serve as impurity traps for self-interstitials in a-Fe. At large values of the stress gradient the spontaneous migration of the A1 atoms from the mixed dumbbells is possible. MeTOAOM fiiammmoro MonenupoBaHm Mccnenymcn a~e p r e~m e c m e XapaIiTepHcTMHH a-meneaa C B O~O H H O M OT HanpRmemii H B rpanxxeme Hanpfimeml. BnHrrHHe rpaaneHTa Hanpnmemii npoRsnReTcfi B TOM, TO a~e p r e~m e c~~l e 6apbepb1 MMrpaqmi ~emy3enb~brx TO MOB no rpanuemy Hanpnweml mrme, qeM npoTm rpaaHeHTa HanpRmeHHil. 3~e p r m MHrpaIIHH CO6CTBeHHbIX M IlpHMeCHbIX MeWy3eJIbHblX aTOMOB aJIIOMHHHJ3 B KpllCTaJrJIe MHrpaU11H aTOMa A1 113 CMeIUaHHOfi raHTeJIH Fe-A1 3HaqHTeJIbHO HHlfCe, 4eM aTOMa Fe I13 3 T O a Me TaHTeJIH, T.e. aTOMbI A1 IIBJIRIOTCFI IlpUMeCHbIMH JIOByllIKaMH HJIR CO6CTBeHHbIX B03MOMeH CIlOHTaHHbI~ yXOa aTOMa A1 113 CMelUaHHOl I'aHTeJIH. ~e m y a e n b~b~x aToMoB B a-meneae. n p k~ ~OJILIIIHX ~H~~~H M R X rpaAvreHTa HanpfillrceHMii H ?t 1 c c.

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It is known that external s t r e s s affects the process of radiation damage in metals. A strong influence of tensile stresses significantly affecting the incubation dose and the void nucleation rate in steel has been confirmed by experimental observations in /l/. In stressed crystals the change of the atomatom collision chain path and as a consequence the space distribution of vacancies and interstitials in atom-atom collision cascades /2 to 4/ has been established by computer experiments (method of molecular dynam.ics) . Simulation results of collision cascades initiated by the primary-knocked atoms (PKA) with comparatively low energies (< 1000 eV) show that the crystal lattice deformations influence the form and s i z e s of the damage region and therefore the number of point defects formed in the cascade. Calculations by the method of molecular dynamics of cascades initiated by high-energy PKA demand great expenditures. Therefore they are carried out by simplified methods, for example, binary collisons /5/. Some parameters (zone s i z e s of spontaneous annihilation of Frenkel pairs, threshold displacement energy Ed, etc.) obtained from experiment or calculated by the method of molecular dynamics are used as a-priori information. The method of binary collisions cannot give a full description of all aspects of radiation damage dynamics but allows to estimate s i z e s of the damage region and the number of formed defects. The employment of this method for cascade calculation in strained crystals needs the correcti& of a-priori information, i. e. E of radiation defects by analytical models of the Kinchin and Pease type /6/ o r TRN + standard /7/. The employment of such models for estimating the number of defects caused by radiation in loaded crystal needs theaccounting of deformation of the crystal structure. It can be fulfilled by changing the model parameters one of which is the displacement threshold energy E An analogous situation occurs when estimating the number d' d' 1) 480082 Alma-Ata, USSR.

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