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

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 gamma/beta phases formed in the MCrAIY 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 beta-phase. Under flexural loads, the failure of coatings showed plasticity and anisotropy characteristics depending on the two laser tracks orientations evaluated.