Venediktov A.N. et. al. 2019 Vol. 21 No. 3

OBRABOTKAMETALLOV Vol. 21 No. 3 2019 113 MATERIAL SCIENCE References 1. Kovenskii I.M., Venediktov A.N. Starenie i stabilizatsiya svoistv gal’vanicheskikh pokrytii [Aging and stabilization of the properties of electroplated coatings]. Omskii nauchnyi vestnik. Seriya: Pribory, mashiny i tekhnologii = Omsk Scientific Bulletin. Series: Equipment, Machines and Technologies , 2010, no. 3, pp. 43–45. 2. Bowen A.W., Leak G.M. Diffusion in BCC iron base alloys. Metallurgical and Materials Transactions , 1970, vol. 1 (10), pp. 2767–2773. DOI: 10.1007/BF03037813. 3. Li M., Kirk M.A., Baldo P.M., Xu D., Wirth B.D. Study of defect evolution by TEM with in situ ion irradiation and coordinated modeling. Philosophical Magazine , 2012, vol. 92, pp. 2048–2078. DOI: 10.1080/14786435.2012.662601. 4. Polukarov Yu.M. Elektrodnye protsessy i metody ikh izucheniya [Electrode processes and methods for their study]. Kiev, Naukova dumka Publ., 1979. 706 p. 5. Nemirov-Danchenko L.Yu., Lipnitskii A.G., Kul’kova S.E. Issledovanie vakansii i ikh kompleksov v metallakh s GTsK-strukturoi [Vacancies and their complexes in FCC metals]. Fizika tverdogo tela = Physics of the Solid State , 2007, vol. 49, no. 6, pp. 1026–1032. (In Russian). Determination of the Effective Diffusion Coefficient of Vacancies in Ultradispersed Electrolytic Iron and its Effect on Heat Treatment Conditions Anatolii Venediktov a, * , Viktor Ovsyannikov b , Nikolai Venediktov c Tyumen Industrial University, 38 Volodarskogo, Tyumen, 625000, Russian Federation a https://orcid.org/0000-0002-6899-4297, annattoliy@gmail.com, b https://orcid.org/0000-0002-7193-7197, vik9800@mail.ru , c https://orcid.org/0000-0001-6175-7312, venediktovan@tyuiu.ru Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2019 vol. 21 no. 3 pp. 106–114 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2019-21.3-106-114 Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov ARTICLE INFO Article history : Received: 18 June 2019 Revised: 05 July 2019 Accepted: 15 July 2019 Available online: 15 September 2019 Keywords : Electrolytic iron Ultra-dispersed coatings Diffusion Diffusion coefficient Annealing Aging Intergrain diffusion Vacancies Dislocations Galvanic coatings ABSTRACT Introduction. Electrolytic iron plating is widely used to improve the wear resistance and hardness of surfaces, as well as restoring worn machine parts. However, the properties of electroplated coatings can change during operation, and even prolonged aging does not lead to stabilization of these properties. Reduction the stabilization time is achieved by heat treatment, the calculation of which regimes for ultra-dispersed coatings should be carried out based on the diffusion laws of point defects. Goal of the work is to calculate the effective diffusion coefficient, taking into account the grain boundary diffusion in the ultra-dispersed electrolytic iron and, on the basis of this coefficient, to find the conditions of heat treatment necessary to stabilize the properties of coatings. Methods of research. Scanning and transmission electron microscopy are used to study the grain structure and intergrain boundaries; thermodynamic calculations are applied in order to find diffusion coefficients; the Comsol Multiphysics program is selected to determine the temperature and time required to stabilize the properties of iron. Results and discussion. An expression for determining the effective diffusion coefficient for ultra-dispersed electrolytic iron, taking into account the influence of intergrain boundaries is obtained. Thermodynamic calculations have shown that, in comparison with the volume coefficient, the effective diffusion coefficient can be two orders of magnitude higher and is largely determined by the size of the grain. Using the method of microstructural analysis, the conditions for obtaining ultradispersed coatings with a large proportion of intergrain boundaries are determined and it is experimentally confirmed that it makes sense to take into account the contribution of grain boundary diffusion, when grain sizes are less than 100 nm, which corresponds to hard conditions of coating deposition . Computer simulation showed that as compared to previously known data, the annealing temperature of ultradispersed iron coatings can be reduced by 50 °C. ______ * Corresponding author Venediktov Anatolii N. , Ph.D. (Engineering), Associate Professor Tyumen Industrial University 38 Volodarskogo str., 625000, Tyumen, Russian Federation Tel.: +7 (904) 490-29-20, e-mail: annattoliy@gmail.com cient of vacancies in ultradispersed electrolytic iron and its effect on heat treatment conditions. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science , 2019, vol. 21, no. 3, pp. 106–114. DOI: 10.17212/1994-6309-2019-21.3-106-114. (In Russian). For citation: Venediktov A.N., Ovsyannikov V.E., Venediktov N.L. Determination of the effective diffusion coeffi