Microscopic and mechanical property evaluation of plasma sprayed Ni80Al20 on AA2024 substrate

NiAl intermetallics are known for their potential use as protective coatings for improving high temperature strength, oxidation resistance, corrosion resistance and hardness. They are widely used in electronic, energy, aerospace and automotive industries as turbine blades, heat sinks, propellers, exhaust cooling systems and turbochargers. NiAl coatings are prepared by using thermal spraying, pack cementation, electroplating, physical vapor deposition and laser cladding techniques. Plasma spraying is preferred for its efficient deposition, high-temperature capability, and precise control over coating properties while minimizing oxidation and substrate distortion. AA2024 alloys have admirable fatigue resistance, strength-to-weight ratio and good machinability finding their application in high performance automotives, marine and aircraft applications. Their wide application is hindered in low temperature and low-cycle fatigue applications used due to their lower ductility, low thermal conductivity, and hot corrosion resistance compared to other aluminum alloys. NiAl coatings will help in enhancing these properties of the alloy when it is exposed in high temperature or corrosive environments. In the present research, Ni-Al (Ni80Al20) powders are atmospheric plasma sprayed on AA2024 substrates. Preliminary characterization on Ni-Al powders is carried out using x-ray diffractometer, laser flash analysis and scanning electron microscopic techniques. After spraying, nickel aluminide coatings will be analyzed by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and nano-indentation techniques. A coating thickness of 100 μm was obtained by plasma spraying. Laminar coating structure is observed with the existence of pores and oxides in the layers. Phase analysis reveals the presence of Al₃Ni₅, AlNi₃, NiAl, Al₂O₃ and NiO. These microstructural features influence the fracture toughness and high temperature stability of the alloy which is required for varied applications. Thus, atmospheric plasma spraying of Ni80Al20 powders was experimented on AA2024 alloy and their microstructure, mechanical properties are evaluated.