Structural Evolution and Mechanical Properties of FeCoNiAlTi HEA Coatings Fabricated by Plasma Surfacing

In order to deeply study the influence of the surfacing current on the microstructure and mechanical properties of FeCoNiAlTi highentropy alloy coatings in the plasma surfacing process parameters， five different surfacing currents (140， 160， 180， 200， 220 A) were used for coating preparation， and the microstructure， hardness， wear resistance and tensile properties of the coatings were evaluated by XRD， OM，SEM， micro-Vickers hardness tester， profilometer， friction wear tester and universal testing machine， respectively.Results showed that the porosity and elemental segregation of the coating were significantly improved with the increase of the surfacing current，but there was no significant effect on the coating phase composition.The coating mainly consisted of the typical FCC solid solution phase and Co3 Ti precipitation phase.When the surfacing current was 180 A， the surface microhardness of the obtained T3 coating was up to 322.77 HV0.2， which was about twice that of the substrate.At the same time， the T3 coating showed the best wear resistance， with a maximum wear depth of only 2.144 μm， an average friction coefficient of 0.362 and the lowest wear rate of 3.83×10－6 mm3/(N·m).In addition， the tensile strength and elongation of the T3 coating were 948 MPa and 26.61%， respectively， showing excellent strength and toughness.