Microstructure and Properties of FeCoNiCuSix High Entropy Alloys

The microstructure morphology, hardness, corrosion resistance and magnetic properties of FeCoNiCuSix high entropy alloys prepared by vacuum arc melting at different Si content were studied. Found by multiple testing methods, the crystal structure of the FeCoNiCuSix high entropy alloy without Si has both FCC and BCC structures. After adding Si, all the structure of the alloy transforms to FCC, and there are differences between the alloys after adding Si, which mainly concentrates in the interdendritic areas and dendritic edges. At the same time, because of the addition of Si, the overall hardness of the alloy very significantly improves. When the content of Si < 0.2, the overall compressive property of the alloy decreases, but when the content of Si > 0.2, the alloy has a certain ductility and compressive strength. Due to the enrichment of Cu, the alloy is easy to form a primary cell at the enrichment of Cu, which reduces the corrosion resistance of the alloy. Meanwhile, a small amount of Si can form a solid solution in the Cu enrichment area, reduce the galvanic effect, and improve the corrosion resistance of the alloy. However, with the increase of Si content in the FeCoNiCuSix high entropy alloy, the corrosion resistance of the alloy will deteriorate and the corrosion rate will accelerate. At the same time, the addition of Si will also have a negative effect on the magnetic properties of the alloy.