Elucidating the microstructural and tribological characteristics of NiCrAlCoCu and NiCrAlCoMo multicomponent alloy clad layers synthesized in situ

High-entropy alloys have received considerable attention owing to their unique structures and properties. In this work, two multicomponent alloy clad layers were synthesized from two equimolar powder mixtures of NiCrAlCoCu and NiCrAlCoMo via an in situ reaction on the surface of the AISI 1050 medium carbon steel using the gas tungsten arc welding (GTAW) method. The microstructure, constituent phases and tribological properties of the clad layers were examined under a field-emission scanning electron microscope (FESEM), an X-ray diffractometer (XRD) and a pin-on-disc rotating tribometer. Experimental results indicate that the microstructure of the NiCrAlCoMo clad layer comprises AlFe0.23Ni0.77, Co6Mo6C2 and Fe63Mo37. The NiCrAlCoCu clad layer has a simple microstructure that consists of only BCC and FCC solid solution phases, with lattice constants of a = 0.288 nm and a = 0.362 nm, respectively. In the NiCrAlCoMo clad layer, the complex geometric effect caused by the vein-shaped reinforcement results in strong mechanical interlocking, which can prevent detachment of the reinforcement during rubbing. Therefore, the wear performance of the NiCrAlCoMo clad layer greatly exceeds that of the NiCrAlCoCu clad layer.