Influence of Al Addition on the Microstructure and Wear Behavior of Laser Cladding FeCoCrNiAlx High-Entropy Alloy Coatings

In order to improve the wear properties of FeCoCrNi high entropy alloy (HEA), laser cladding was applied to fabricate FeCoCrNiAlx HEA coatings with different Al additions. The Al-modified coatings exhibited excellent metallurgical bonding interfaces with the substrates. The microstructure of FeCoCrNiAl0.5 coating was the same as of the FeCoCrNi coating: face-centered cubic (FCC). However, the microstructure of FeCoCrNiAl was different: body-centered cubic (BCC) with more Al atoms distributed inside the grains. As the Al content in the coating was increased, the hardness increased as well from 202 to 546 HV0.2, while CoF and wear rate decreased from 0.62 to 0.1 and from 8.55 x 10(-7) to 8.24 x 10(-9) mm(3)/(Nm), respectively. The wear mechanisms changed from the mixture of abrasive, adhesive, and oxidative wear patterns to the mixture of abrasive and oxidative patterns. Such a change indicates that the Al addition indeed improved the wear resistance of FeCoCrNiAlx HEA coatings. Our results expand knowledge on HEA coating applications as wear-resistant materials in various applied industrial fields.