Elucidating the microstructure and wear behavior for multicomponent alloy clad layers by in situ synthesis

High-entropy alloys with a wide range of novel microstructures and properties are under extensive development. In this study, two equimolar powder mixtures of NiCrAlCoW and NiCrAlCoSi were prepared as cladding materials. They were clad by gas tungsten arc welding on AISI 1050 medium carbon steel substrate to form an in situ synthesized multicomponent clad layer. The microstructure, chemical composition and constituent phases of the clad layers were characterized by FESEM, EPMA and XRD, respectively. A rotating tribometer was employed to evaluate the tribological properties of the clad layers. Experimental results demonstrate that the NiCrAlCoW clad layer is composed of W (precipitates and residual particles), AlNi and Cr15.58Fe7.42C6. The NiCrAlCoSi clad layer contains only a BCC phase. The two clad layers exhibit high hardness, caused by precipitation hardening with different precipitates. The NiCrAlCoW clad layer exhibits strong mechanical interlocking, which results from the complex phase and microstructure of the NiCrAlCoW clad layer. During rubbing, the in situ phase transformation of the NiCrAlCoSi clad layer induces the softening of the matrix. Therefore, the wear performance of the NiCrAlCoW clad layer is better than that of the NiCrAlCoSi clad layer.