Microstructure and Properties of CeO2-Modified FeCoCrAlNiTi High-Entropy Alloy Coatings by Laser Surface Alloying

Abstract

The FeCoCrAlNiTi high-entropy alloy (HEA) coatings modified by CeO2 were synthesized on 304 stainless steel substrate with Co-Cr-Al-Ni-Ti-xCeO2 powders by laser high-entropy alloying. The phase composition, microstructure and nano-mechanical and wear properties of FeCoCrAlNiTi-based HEAs were investigated by performing XRD, SEM, EBSD, nanoindentation testing and wear resistance tests. The results displayed that the FeCoCrAlNiTi-xCeO2 HEA coating only had simple FCC and BCC solid solution phases. The microstructure of the FeCoCrAlNiTi-xCeO2 exhibited typical dendrite and interdendritic structures, and the addition of CeO2 resulted in the refined microstructure of the alloyed coating. It was found that BCC phase structure predominantly distributed at the grain boundaries in the HEAs. For the 1 wt.% CeO2 adding HEA, the ratios of the hardness (H) and elastic modulus (E) were much higher than that of FeCoCrAlNiTi HEA coating, indicating that it had the satisfactory property for resistance to scoring and plastic deformation. The wear mechanisms were abrasive, oxidation and adhesive. Among of the three samples, FeCoCrAlNiTi-1 wt.% CeO2 HEA coating displayed the best wear resistance, and the specific wear rate and wear volume loss were 2.748 × 10–5 mm3/N m and 3.71 × 106 μm3, respectively.