Phase evolution and wear mechanism of AlCoCrFeNiSix high-entropy alloys produced by arc melting

Considerable attention has been paid to high-entropy alloys due to their unique structure and promising properties. In this study, AlCoCrFeNiSix (x = 0, 0.5, 1.0, 1.5, and 2.0 in at.%, respectively) high-entropy alloys were synthesized by an arc melting under an argon atmosphere, and the effects of Si addition on the phase types, microstructure and properties were investigated. With increasing Si content from 0 to 2.0, the phase transformed from BCC and FCC to the BCC and Cr3Si phases, and a large number of nanoscale-modulated structure forms due to the introduction of Si element. The interdendrite region shows a higher concentration of Cr, Fe, and Si elements, while the dendrite shows a higher concentration of Al, Co, and Ni elements. The hardness increased from 498 to 908 HV with the increase Si content, which is mainly attributed to the increase of strong BCC, solid solution strengthening effect and precipitation of nanophase. The least mass loss of the alloys is 9.6 mg with the highest Si content, indicating that the wear resistance of the AlCoCrFeNiSix enhanced with addition Si.