Yurkova A. Specific Features of Nanostructure and Mechanical Properties of a-Fe, Resulted from Severe Plastic Deformation by Friction.

In the thesis the important scientific and technical problem of nanocrystalline structure formation in bcc iron subjected to severe plastic deformation by friction (SPDF) in different gas atmosphere (argon, air, ammonia) was decided on the base of the results of fundamental researches (investigations) by optical microscopy, X-ray diffraction analysis, transmission and scanning electron microscopy and micromechanical testing, including nanoindentation technique. The effect of the structural state changes on the features of diffusion and phases transformations in the indicated conditions, and also on the complex of mechanical properties of material in the nanocrystalline state is generalized. It was found the necessary conditions (temperature, strain and strain rate) to obtain the nanocrystalline structure of bcc Fe during SPD by friction. These results are important both for the current basic research and for application in engineering practice.