Interfacial Reaction of CoCrFeNi High Entropy Alloy in Molten Al

Abstract

In this paper, we studied the element diffusion behaviors of the multi-principal CoCrFeNi high entropy alloy in molten Al at 700°C. Microstructure, structure and microhardness in the diffusion interfaces of CoCrFeNi and Al are studied by the X-ray diffraction, the scanning electron microscopy, the energy spectrometry, and the microhardness tester. The results showed that a complex chemical reaction occurred at the interface between the high-entropy alloy and the Al. A mixture of FCC + BCC solid solution layer was first formed. Then a bulk Al13Cr2 compound formed near the Al of the solid solution layer. With the increase of dipping time, the thickness of the solid solution layer remained unchanged, and the compounds gradually changed into spheres distributed in the Al matrix. The formation of BCC structure makes the hardness of the solid solution layer up to 450HV, and the existence of the compound also increases the hardness of the Al matrix significantly.