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Item In Situ High-Temperature X-ray Diffraction Study on Atmospheric Plasma and Detonation Sprayed Ni-5 wt.%Al Coatings(Springer, 2023) Purushotham, N.; Santhy, K.; Suresh Babu, P.; Govindarajan, G.; Rajasekaran, R.In situ high-temperature x-ray diffraction (HT-XRD) was used in the present study to assess the coefficient of thermal expansion and recrystallization of Ni-5 wt.%Al coatings. Atmospheric plasma spray (APS) and detonation spray (DSC) techniques were used to deposit Ni-5 wt.%Al coatings on IN718 substrates. The coatings were examined using HT-XRD at ambient conditions (25 °C) up to high temperatures (1150 °C) under a vacuum pressure of around 10−4 mbar. Coefficients of thermal expansion (CTE), crystallite size (D) and lattice strain (ε) were determined by the Scherer and Williamson-Hall (W-H) method with a uniform strain model (UDM) using x-ray peak profile analysis (XPPA). The microstructure of the Ni-5 wt.%Al coatings was analyzed by field emission scanning electron microscopy (FESEM). No phase changes were observed in either coating, as the Ni-5 wt.%Al coatings consisted mainly of γ-Ni crystals with a face-centered cube (FCC) phase in both coating techniques. Lattice parameters as a function of temperature were used to calculate linear thermal expansion coefficients. The linear thermal expansion of Ni-5 wt.%Al coatings deposited by both thermal spray methods was discussed on the basis of process-induced microstructures. © 2023, ASM International.Item High temperature sliding wear behavior of detonation sprayed Ni-5wt%Al coating(Elsevier Ltd, 2023) N, P.; N.l, P.; P, S.B.; G, S.; Rajasekaran, R.The tribological behavior of detonation (DSC) sprayed Ni-5%wtAl coatings at room temperature (25 °C) and elevated temperature (850 °C) has been studied in this work. Dry sliding wear experiments were done by using alumina (Al2O3) ball-on-disc tribometer. FESEM-EDS and a non-contact 3D profilometer microanalysis were used to evaluate the worn scar and wear rate and identify the wear mechanism. X-ray diffraction (XRD) investigation indicated that the Ni-5wt%Al coating predominantly consists of γ-Ni phases at 25 °C and 850 °C conditions. The phase evolution, thermal expansion, crystallite size, and lattice strain were evaluated using in-situ high-temperature X-ray diffraction (HT-XRD). The crystallite size (D) and lattice strain (ε) were determined by Williamson-Hall analysis using a uniform deformation model (UDM), employing X-ray peak profile analysis (XPPA). In high-temperature conditions, the thermal expansion mismatch between the coating and substrate is negligible, with reduced spallation and cracking at the interface. The findings of the wear tests revealed that as the temperature increased, the coefficient of friction (CoF) and wear rate (ω) significantly decreased as the wear mechanism changed from abrasive to adhesive. The improvement of wear resistance of Ni-5wt%Al coating at high temperatures has been evaluated and discussed from the perspective of thermal expansion and tribo-layer formation. © 2023 Elsevier B.V.