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Streszczenie:
In this paper, the effect of hafnium, titanium, and molybdenum addition on the microstructure and properties of the aluminide layers deposited by using a chemical vapor deposition process on IN 713C nickel superalloy substrate was discussed. A multi-component aluminide diffusion layer containing Ni–Al, Al–Ti–Ni, and hafnium-rich phases was successfully formed by aluminizing IN 713C nickel superalloy. Subsequently performed corrosion resistance tests confirmed the beneficial effect of the aluminide layer deposited on IN 713C as compared to substrate material. Anticipating improved mechanical response of coated material, density functional theory calculations were performed. It was found that a single Hf/Ti/Mo atom prefers to be positioned within the Al sublattice in the NiAl, and Ni3Al phases. This justifies the presence of the experimentally observed Ni3Hf phase in the Hf-enriched IN 713C. The Hf modification effects on the NiAl, and Ni3Al were further discussed based on the changes of the elastic constants Cij, bulk modulus B, and shear modulus G. The presence of Hf in NiAl causes a decrease of phase’s C12 and C44 values, and increase in the C11 value. It was found that Hf modification of the Ni3Al causes a decrease in the Cij values and a slight decrease of phase’s B/G ratio, indicating a less ductile character of modified phase decohesion.

Słowa kluczowe:
IN 713C, CVD, Aluminide layer, Corrosion resistance, SEM, Ab initio calculations

Streszczenie:
The study investigated the effect of the oxidation–reduction cycles on the structure and corrosion resistance of the Haynes 282 nickel superalloy at ambient and elevated temperatures. The comparative studies were performed on specimens produced by the Powder Bed Fusion-Laser Beam (PBF-LB) process and those in the as-received state. The microstructure of the PBF-LB specimens was studied using optical and scanning electron microscopy, whereas the chemical composition of the scale formed after isothermal oxidation in an air atmosphere at 750°C was analysed using energy-dispersive X-ray spectroscopy and X-ray Photoelectron Spectroscopy. The phase composition of the formed scale was determined by X-ray diffraction. Laboratory-induced hydrogen atmosphere was adopted through cathodic charging. A comparison of corrosion resistance was carried out on two types of Haynes 282 specimens, before and after the oxidation and cathodic charging processes. It was found that PBF-LB process could be effectively used to manufacture Haynes 282 nickel superalloy with low porosity and a fine crystalline microstructure. The low-porous, fine-crystalline microstructure of the tested specimens produced by the PBF-LB technique exhibited good resistance to electrochemical corrosion, slightly lower than wrought Haynes 282 nickel superalloy specimens.

Słowa kluczowe:
corrosion, DMLS, haynes 282 nickel superalloy, hydrogen, oxidation