Changes in the Structure of a Thermal Protective Nickel Aluminide Coating under the Influence of a Single Thermal Laser Pulse

• Published in: Inorganic materials : applied research 2022, Vol.13 (3), p.740-744
• Main Authors: Berdnik, O. B., Kikin, P. Yu, Perevezentsev, V. N., Razov, E. N., Rusin, E. E., Tsareva, I. N.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Boundaries; Chemistry; Chemistry and Materials Science; Functional Coatings and Surface Treatment; Heat flux; Heat transfer; Inclusions; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Intermetallic compounds; Intermetallic phases; Irradiation; Manganese; Materials Science; Microcracks; Microstructural analysis; Nickel aluminides; Nickel base alloys; Nickel compounds; Niobium; Phase composition; Photomicrographs; Protective coatings; Protective structures; Pulse duration; Radiation; Solid solutions
• ISSN: 2075-1133; 2075-115X
• DOI: 10.1134/S2075113322030078

The regularities of changes in the structure and phase composition of a thermal protective nickel aluminide coating (45% Ni, 14% Al, 22% Co, 18.9% Cr, 0.15% Fe, 0.14% Nb, 0.09% Y, 0.06% Ca, 0.01% Mn, 0.15% C, 0.15% Si, and 0.006% S) after exposure to short-term pulsed heat fluxes of various power created by the radiation of an LRS-150A pulse-periodic laser with a radiation wavelength λ = 1.06 μm and a pulse duration τ = 12 × 10 –3 s were studied. The radiation energy was E = 5, 10, and 15 J. Microstructural analysis and the elemental composition of the resulting coating were carried out as well as analysis of the phase composition. X-ray microanalysis of the coating was also carried out. In the initial state and after irradiation of the coating with a heat flux power P = 7 × 10 3 W/cm 2 , light microregions are observed on the micrographs of the surface. These regions do not have clearly defined external boundaries and consist of the NiAl phase and a small amount of the Ni 3 Al phase with the presence of inclusions of particles containing a solid solution of Ni–Co–Cr. After irradiation of the coating with heat fluxes of higher power ( P = 1.7 × 10 4  W/cm 2 and P = 2.2 × 10 4 W/cm 2 ), large convex formations appeared on its surface, consisting mainly of Ni 3 Al and NiAl phases. On micrographs of the surface, they appear as white areas with well-defined outer boundaries. The content of the Ni 3 Al phase in them increased in comparison with the initial state and the content of the NiAl phase decreased, while the particles of inclusions of Ni, Co, and Cr disappeared. It can be assumed that an increase in the Ni 3 Al content is associated with the dissolution of particles of a solid solution of Ni–Co and Cr in the melt and the subsequent diffusion of nickel into the NiAl phase. When exposed to a heat flux of power P = 2.2 × 10 4 W/cm 2 , microcracks appear on the areas of the coating surface covered with aluminum oxide.