In the paper some functional properties (hardness and oxidation resistance) of platinum and palladium modified aluminide coatings deposited by the CVD method on a nickel-based superalloy were determined. The platinum and palladium microlayers, 3 µm thick were deposited by electroplating process. The heat treatment of electroplating microlayers was performed for 2h at the temperature 1050• C in an argon atmosphere as to increase adhesion between the coating and the substrate. The low activity CVD aluminizing process of platinum heat treated coatings 3 µm thick at the 1050• C for 8h using IonBond equipment was performed. The effects of aluminizing process were verified by the use of an optical microscope (microstructure and coating thickness); a scanning electron microscope and an energy dispersive spectroscope (chemical composition of the surface and cross-section of the modified aluminide coating). The hardness measurements on the cross-section of nonmodified and platinum or palladium modified aluminide coatings were performed. Oxidation tests of modified aluminide coatings at the 1100• C for 1000 h in the air atmosphere were carried out. On the grounds of the obtained results it was found that the main phase of the platinum modified aluminide coating is β-(Ni,Pt)Al. Consequently, the palladium modification of aluminide coating causes the formation of β-(Ni,Pd)Al phase. The platinum modified aluminide coating has better oxidation resistance than nonmodified and palladium modified aluminide coating. The XRD analysis of the surface of oxidized platinum modified aluminide coating confirmed the presence of the thermodynamically stable oxide layer Al 2 O 3 , that has good protective properties. The oxides of NiAl 2 O 4 , Al 1.98 Cr 0.02 O 3 and TiO 2 were found on the surface of the palladium modified aluminide coating after 1000 h oxidation at the 1100• C the in the air atmosphere. Keywords: platinum and palladium modified aluminide coating, low-activity CVD process, Ni-base superalloy, oxidation resistance W pracy określono niektóre właściwości użytkowe (twardość oraz żaroodporność) warstwy aluminidkowej modyfikowanej platyną i palladem wytworzonej metodą CVD na podłożu nadstopów niklu, polikrystalicznym Inconel 713 LC i monokrystalicznym -CMSX 4. Powłokę platyny i palladu (grubość -3µm) wytworzono metodą galwaniczną. Poprawę przyczepności powłoki galwanicznej do podłoża uzyskano przez wygrzewanie w temperaturze 1050• C w czasie 2 h w atmosferze argonu. Warstwę aluminidkową wytworzono w procesie niskoaktywnym CVD (temperatura -1050• C, czas -8h). Efekty procesu aluminiowania weryfikowano w badaniach mikroskopowych (mikrostruktura i głębokość warstwy) oraz w analizie składu chemicznego na powierzchni i przekroju warstwy modyfikowanej. Pomiary twardości prowadzono na przekroju niemodyfikowanej warstwy aluminidkowej oraz warstwie modyfikowanej platyną i palladem. Próbę zmęczenia cieplnego wykonano w temperaturze 1100• C i w czasie 1000 h w atmosferze powietrza. Analiza uzyskanych wyników badań pozwała stwierdzić, że g...

Inconel 718 is a precipitation hardenable nickel-iron based superalloy. It has exceptionally high strength and ductility compared to other metallic materials. This is due to intense precipitation of the γ' and γ" strengthening phases in the temperature range 650-850°C. The main purpose of the authors was to analyze the aging process in Inconel 718 obtained in accordance with AMS 5596, and its effect on the mechanical properties. Tensile and hardness tests were used to evaluate the mechanical properties, in the initial aging process and after reheating, as a function of temperature and time respectively in the ranges 650°-900°C and 5-480 min. In addition, to link the mechanical properties with the microstructure transmission microscopy observations were carried out in selected specimens. As a result, factors influencing the microstructure changes at various stages of strengthening were observed. The authors found that the γ'' phase nucleates mostly homogenously in the temperature range 650-750°C, causing the greatest increase in strength. On the other hand, the γ' and δ phases are formed heterogeneously at 850°C or after longer annealing in 800°C, which may weaken the material.

In the present study, microstructure investigation of aluminide coatings after platinum modification deposited by CVD method on Inconel 713 LC Ni-base superalloys were performed. The platinum coatings 3 and 7 m thick were deposited by electroplating process. The diffusion treatment of platinum electroplating coatings at the temperature 1050 °C was carried out for 2h. The low-activity CVD aluminizing of heat treated coatings at the temperature 1050 °C was conducted for 8 h. On the grounds of the obtained results it was found that microstructure of diffusion treated platinum electroplating coatings 3 m and 7 m thick consisted of two phases: γ-Ni and (Al0.25Pt0.75)Ni3. The low activity CVD aluminizing of diffusion treated platinum electroplating coatings 3 and 7 m thick enables the diffusion coating obtaining. The main constituent of aluminide coatings was (Ni,Pt)Al phase.

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