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Information × Registration Number 0205U000966, 0102U000420 , R & D reports Title Stady of influence of electronic structure and short range atomic order on thermodynamic phases stability physical-chemical and physical-mechanical properties of corrosion-resisting and functional iron-based and nicel-based alloys popup.stage_title Head Gavriljuk Valentin Gennadievich, Доктор технічних наук Registration Date 18-02-2005 Organization Institute for metal physics NAS Ukkraine popup.description2 The main aim of the research work was to elaborate the physical concepts of engineering of corrosion-resistant and functional iron- and nickel-based alloys. The research of correlation between electronic structure, short range atomic order, thermodynamic stability of phases, both functional and mechanical properties of these alloys was carried out. It is shown that alloying of fcc iron-based alloys by nitrogen+carbon increases significantly the concentration of free electrons, i.e. contributes to metallic character of interatomic bonding. This phenomenon is appeared in increase of thermodynamic stability of solid solution and creates a perspective for development of economically alloyed corrosion-resistant high-strength austenitic steel. It is determined that the positive influence of silicon on functional properties of Fe-Mn shape memory alloys is explained by a correlation between increase of concentration of free electrons induced by silicon and Fe-Si short range atomic order. Atoms of Si gather round Fe atoms thus atoms of Mn leave solid solution and form clusters with structure ?-Mn. The formation of concentration inhomogeneities and precipitations at ageing or thermomechanical training increases the shape memory effect due to opposite stresses arising at previous deformation and assists reversible deformation at the next heating. Three main hypothesis of hydrogen embrittlement of stable austenitic steels are tested: hypothesis about hydrogen-caused decohesion, pseudohydrides and plasticity localized by hydrogen. It is shown that hydrogen increases concentration of free electrons as well as nitrogen. This increasing decreases locally a shear modulus so that the start stress of dislocation sources decreases, dislocations become more mobile. It causes localized and increased plasticity, early crack opening and pseudo brittle character of fracture. Magnetic shape memory of Ni-Mn-Ga alloys is studied. The magneto-thermal effect of shape memory is discovered and the Ukrainian patent application is submitted.56355635 Product Description popup.authors popup.nrat_date 2020-04-02 Close