In modern gas-turbine units increase of gas working temperature leads to shortening of blade service life. For this reason their repair becomes a priority. Retailoring of single-crystal blade tip by hardfacing is a rather complicated task. In order to select suitable filler material, thermal cycling tests of samples of deposited welds on CMSX-4 alloy with a single-crystal structure have been performed. Evolution of the structure under the conditions of high-temperature cyclic oxidation is considered. Selection of filler material, which ensures high temperature resistance and stability of weld metal structure, was optimized. These requirements are satisfied by Co-Ni-based material, which was earlier tried out and proved to be very good in complex technology of repair of a blade from ZMI-3U alloy. The technology includes airfoil tip retailoring by hardfacing with subsequent deposition on the item surface of a high-temperature metal coating by electron beam deposition to ensure the required service properties of the item. 18 Ref., 4 Tables, 10 Figures.

Проанализированы и обработаны экспериментальные данные термодинамических параметров широкого ряда отечественных и зарубежных литейных жаропрочных никелевых сплавов пяти поколений. Получены математические регрессионные модели для прогнозирующих расчетов термодинамических параметров, которые могут использоваться при разработке новых перспективных сплавов или модернизации существующих промышленных сплавов. Библиогр. 25, табл. 2, ил. 5. К л ю ч е в ы е с л о в а : литейные жаропрочные никелевые сплавы; система легирования; термодинамические параметры; математическая регрессионная модель

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The brittleness of structural ceramic materials prevents their wide application. In this connection, three basic approaches are used: (i) examine mechanical macro-and micro-behavior, (ii) improve production processes, and (iii) design new structures with improved defect tolerance [1]. The idea of maximally decreasing the concentration of structural defects, which determine the main mechanical properties, dominated among researchers at a certain stage of developing high-strength oxide ceramics. After some minimal decrease in the defect concentration had been reached, this idea ran its course. Establishing the ZrO 2 transformation hardening effect in 1975 [2] gave way to a new class of ceramic materials (Mg−PSZ, Y−Ce−TZP, ZTA) based on the martensitic phase transformation of metastable tetragonal ZrO 2 solid solutions (T-ZrO 2 ) into monocline ZrO 2 solid solutions (M-ZrO 2 ) initiated by the stress field at the tip of a crack occurring under loading. The approach to the development of crack-resistant ceramic materials could be changed owing to the creation of ceramics with special microstructures that improved their strength and fracture toughness.One of the most attractive approaches is to design materials consisting of layers with different properties. The mechanical properties of a layered material are better than the individual properties of its components. Different composites (symmetric and asymmetric, with different thickness ratios, different composition gradients at the interface of two layers, layup, etc.) are used in developing layered ceramic materials. One area is to develop layered materials with weak interfaces between layers without residual stresses or layered materials in which dense and high-strength external layers are combined with crack-resistant internal layers. Another area is to develop materials in which residual compressive stresses develop in the external layers when cooled down because of different thermal expansion coefficients (TEC) of individual layers. When loaded, the compressed layers can retard cracks, improve viscosity and fracture energy, and thus improve the reliability of ceramics. This results in layered ceramics with much better properties than those of monolith ceramics [3].