Optimization of Fe3Al intermetallic cold gas spray coatings: Microstructural characterization

Cold Gas Spray (CGS) is increasingly applied in industry and becoming even more important in advanced applications. This study focuses on the use of CGS process optimization of metal transitional aluminides, specifically Fe 3 Al. These low-cost materials have high resistance to sulfidation and carburizing atmospheres, as well as excellent oxidation resistance at high temperatures. Therefore, this study aims to deposit Fe 3 Al powders via CGS onto steel substrates, evaluating the use of Helium (He) and Nitrogen (N 2 ) as carrier gases, examining the influence of particle size distribution of two powders. The coatings have been optimized by studying the splat formation and their microstructures to better understand the deposition process. The best coatings have been characterized by microstructural analysis with scanning electron microscopy and energy dispersive X-ray spectroscopy, also measuring their microhardness. The work concludes that Fe 3 Al coatings have been successfully deposited by CGS. Therefore, dense coatings were achieved by using both He and N 2 as carrier gases for the fine powder. Even so, the use of He as the carrier gas produces thicker and harder coatings, as particles reached higher velocities, allowing also to produce a good coating with the coarse powder. • Fe 3 Al coatings have been successfully deposited after optimization by Cold Gas Spray using Nitrogen and Helium as carrier gases. • The use of Helium as carrier gas is more favorable, allowing higher velocities, but dense coatings have been also obtained using Nitrogen as carrier gas with the smaller powder. • A study on the splat formation has been performed to better understand the deposition process. • The EDS results confirm that the CGS process allows manufacturing Fe 3 Al coatings without oxidation and preserves the initial phases of the feedstock powders. • The optimal coating obtained was dense (porosity = 0.4%), with a thickness of 786 ± 81 μm and a Vickers hardness of 407 ± 6 HV 0,2 .