![]() ![]() O poryadke vydachi spravok dlya vyezda za granitsu inzhenerno-tekhnicheskim i agronomicheskim spetsialistam (1924) // Izvestiya NKT. Instruktsiya NKT SSSR №19/43 ot 31 dekabrya 1923 g. ![]() Rabota kommun sel'skokhozyaystvennykh immigrantov v SSSR // Sel'skokhozyaystvennaya zhizn'. Smoluchowski, “Imperfections in Nearly Perfect Crystals” (J. Huntington, Acta Metallurgica 1 (1953) 513.ĭ. Kennedy, “Introduction to Radiochemistry”. Van Nostrand Co, Inc, New York, 1956) pp. Murphy, “The Mathematics of Physics and Chemistry” (D. Shewmon, “Diffusion in Solids” (McGraw-Hill, New York, 1963) pp. Mirkin, “Handbook of X-ray Analysis of Polycrystalline Materials” (Consultants Bureau, New York, 1964) pp. Crank, “The Mathematics of Diffusion” (Oxford at the Clarendon Press, London, 1956) pp. Vysshikh Uchebnykh Zavedenii Tavetnaia Metallurgiia 4 (1965) 123. By using an estimated value of the bulk diffusion coefficient, the Suzuoka analysis permitted direct calculation of the grainboundary diffusion coefficient, and can be represented by: D g.b.=4.57×10 2 exp−(71,000/ RT). The Fisher grain-boundary diffusion analysis and the Suzuoka analysis gave apparent grain-boundary diffusion activation energies of 74 Kcal/mole and 71 Kcal/mole respectively. ![]() The first obeyed a bulk diffusion law, originated at the specimen surface, demonstrated anomalously low diffusion coefficients, dominated to a depth of about 0.5 μm, and could be represented by the expression: D vol=1.90×10 −6 exp−(88,000/ RT).Īutoradiography demonstrated that the second mechanism was grain-boundary diffusion which dominated at depths greater than 1 μm. The existence of two clearly delineated diffusion mechanisms was demonstrated from the shape of the activity versus penetration curves. The necessity for extended diffusion anneal times was eliminated by using a submicron sectioning technique, and the diffusion penetration depth was determined by spectrophotometric W V thiocyanate analysis of the sample sections. Dense, hot pressed tungsten carbide specimens were used to study the self-diffusion of 14C into WC in the temperature range 2238 to 2643 ° K. ![]()
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