Mechanical and microstructural characterization of MCrAlY coatings produced by laser cladding: The influence of the Ni, Co and Al content

• Published in: Surface & coatings technology Vol. 338; pp. 22 - 31
• Main Authors: Pereira, J.C., Zambrano, J.C., Rayón, E., Yañez, A., Amigó, V.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25-03-2018; Elsevier BV
• Subjects: Aluminum; Austenitic stainless steels; Beta phase; Coatings; Ductility; Elastic modulus; Emission analysis; Field emission; Laser beam cladding; Laser cladding; Laser deposition; Laser sintering; Materials elasticity; MCrAlY; Mechanical properties; Microhardness; Microstructure; Modulus of elasticity; Nanoindentation; Nanoindentation hardness; Nickel; Spraying; Substrates; Thermal barrier coatings; X-ray diffraction; Nanoindentation hardness; MCrAlY; Thermal barrier coatings; Elastic modulus; Laser cladding; Ductility
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.01.073

Laser metal deposition (LMD) and laser cladding (LC) are alternative methods to thermal spraying processes to produce dense, high-quality coatings. In this work, two MCrAlY coatings (M = Ni + Co) have been prepared onto stainless steel substrate using a coaxial LC technique under two different Ni/Co and Al proportions. The mechanical properties were then evaluated with microhardness, nanoindentation, and three-point bending tests. The microstructure and composition of coatings were characterized by X-ray Diffraction (XRD) analysis and Field Emission Electron Microscopy (FESEM) coupled to an Energy Dispersive Spectroscopy (EDS) detector. The study revealed that the γ/β phases formed in the MCrAlY coating microstructure result in a lower elastic modulus than the austenitic stainless steel substrate, while an inverse behavior for hardness was observed due the presence of the aluminum-rich β-phase. Under flexural loads, the failure of coatings showed plasticity and anisotropy characteristics depending on the two laser tracks orientations evaluated.
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•We obtained dense MCrAlY coatings by overlapping coaxial laser cladding.•The mechanical properties and microstructure in as-built condition were studied.•Adequate ductility was observed in the three-point bending tests.•There was an anisotropy in flexural behavior according to the direction of laser tracks.•Coaxial laser cladding is a good alternative to thermal spray processes for bond coats.