Self-diffusion in non-stoichiometric intermetallic compounds with the B2 and structures has been considered. It was shown that the thermal and compositional anti-structure defects substantially affect the diffusivity forming `anti-structural bridges' for a vacancy migration without additional disordering of the intermetallic compound. While this contribution was found to have a percolation nature for both sublattices in the case of the B2 structures, the percolation is to be taken into account only for diffusion of the minor element in intermetallic compounds with the structure. The numerical calculations were carried out for the CoGa triple-defect intermetallic compound. Critical exponents and fractal characteristics of percolation clusters were estimated. Values of the threshold anti-structure defect concentrations are for B2 structures and for the -sublattice of the compound with the structure. Owing to the temperature dependence of defect concentration the percolation threshold is temperature dependent also and, e.g., corresponds to composition at T = 1323 K. The theoretical predictions are compared with experimental data.
Mass transfer in iron and nickel stimulated by pulsed laser radiation is studied by the radioactive isotope method. New experimental results are obtained and an analysis in terms of kinetic equat.ions is given. It is shown: (a) exposure of the metal surface to high intensity pulsed laser radiation leads to an accelerated atomic migration into the sample; (b) an effective retardation, the value of which depends upon the presence of crystalline defects in metals has an esaential influence on the atomic migration rate stimulated by the laser; (c) multiple laser loading results in a concentration maximum formed inside the sample, the depth displacement of which depends upon the energy of light flux and the number of pulsed loadings.
A model of diffusion anisotropy appearance in a textured polycrystalline aggregate under the grain boundary diffusion preponderance (the C type of kinetic) has been suggested. Although in the textured polycrystal there exists a distribution over 5 degrees of freedom describing the grain boundaries macroscopically, it is the misorientation distribution that has been shown to may give rise to the diffusion anisotropy. Presence of small-angle boundaries and a certain, sufficiently sharp texture is the key moment at this.PaCCMOTpeHa MOAeJlb B03HHKHOBeHHB aHH30TpOIIHH nH@@YSHH B TeKCTypHpOBaHOM IIOJIHKpHCTanJlMWCKOM arperaTe B yCJlOBHsX n p e o 6 n a n a~a~ 3epHOrpaHHqHOk AH@@)'3HH. MaKpOCKOIIHWCKM CBO6Onbi. nOKa3aH0, STO npH OnpeAeneHHbIX yCJlOBHRX paCIIpeneJleHHe pa300pHeHTHpOBOK AOJIXHO npHBOnHTb K B03HMKHOBeHHH3 aHH30TpOnHH nM@@y3MH. npH 3TOM HaJlHSHe B CHCTeMe MaJIOyrnOBbIX rpaHuqbr 3 e p e~ B TeKcTypapoeaHoM arperaTe x a p a~~e p~3 y m~c~ pacnpeneneHueM no ~B T H cTeneHxM rpaHMu M onpeAeneHHok, nocTaTowio O C T P O~ TeKcTypbi urpaeT onpenensmuym ponb.
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