High-entropy AlCoCuFeNi Matrix Composites Reinforced with Tungsten Carbide

In the present study, metallic-ceramic composites were fabricated, with an equimolar high-entropy AlCoCuFeNi alloy as the matrix, and tungsten carbide WC (5 and 10% by volume) as the reinforcing phase.Induction melting and arc melting techniques were used for composite preparation.The metallic matrix of the composite exhibited a twophase structure consisting of FCC and BCC solid solutions.Microscopic investigations revealed a dendritic microstructure of the matrix, in which the WC particles were distributed non-homogeneously, regardless of the melting method.Strong precipitation of the chemical composition in the matrix was observed, with interdendritic regions enriched in copper and dendrites enriched in aluminium, nickel and iron.Additionally, besides WC particles, two types of precipitates, with various morphology, were observed in the matrix.The addition of tungsten carbide particles resulted in an increase in the composite hardness from approximately 273 HV for the high-entropy alloy to as high as 332 HV for the composite.The appearance of the precipitates can be attributed to the chemical reaction between the liquid matrix and WC, resulting in the formation of complex carbides.