The CrFeNbTiMox refractory high-entropy alloy coatings prepared on the 40Cr by laser cladding

Abstract

In order to improve the performance of 40Cr coal mining cutter teeth, the CrFeNbTiMox (x = 0.2, 0.4, 0.6, 0.8, 1) refractory high entropy alloy (RHEAs) coatings were prepared on the 40Cr by laser melting. The effects of the Mo on the phase, microstructure, hardness, wear and corrosion resistance of the coatings were investigated. The results show that the coatings consist of BCC (Im3m), C14-Laves (P63/MMC), C15-Laves (Fd3m) and ordered B2 phase (Pm3m). The BCC phase increased and the C14-Laves phase decreased as the Mo element content increased. The central part of the coating is mainly composed of dendrites and some swelling crystals, the dendritic areas increase and the swelling crystals decrease with the increase of Mo elements. The Mo and Nb elements are mainly concentrated in the dendritic areas, and the Cr and Fe are enriched in the interdendritic areas. With the increase of the Mo element, the hardness of the coating increased from 676 HV to 841 HV, which is about 3.7 times higher than that of the substrate. Dry sliding friction and wear tests show that the wear resistance of the coating improves with the increase in Mo. The Mo1 coating has the lowest wear loss weight, wear volume and wear rate. In the 3.5 % NaCl solution, the polarization curves and the EIS fitting results show that the corrosion resistance of the coating improves with the addition of Mo elements. The hardness, wear and corrosion resistance of the 40Cr substrate is significantly improved due to the refractory high entropy alloy coating.