Microstructure and corrosion resistance of hafnium-doped aluminide layers deposited on IN 713C nickel alloy using CVD method: experimental and ab initio studies

Abstract 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 Ni 3 Al phases. This justifies the presence of the experimentally observed Ni 3 Hf phase in the Hf-enriched IN 713C. The Hf modification effects on the NiAl, and Ni 3 Al were further discussed based on the changes of the elastic constants C ij , bulk modulus B , and shear modulus G . The presence of Hf in NiAl causes a decrease of phase’s C 12 and C 44 values, and increase in the C 11 value. It was found that Hf modification of the Ni 3 Al causes a decrease in the C ij values and a slight decrease of phase’s B / G ratio, indicating a less ductile character of modified phase decohesion.