Microstructure and mechanical properties of a GH3536/SS304 joint brazed with a Co25Fe25Mn5Ni25Ti20 eutectic high-entropy alloy filler

Abstract

To realize a high-strength connection between dissimilar metals, a eutectic high-entropy alloy (EHEA), Co25Fe25Mn5Ni25Ti20 was used as a novel filler to braze GH3536 and SS304. Its typical microstructure and evolution mechanism were investigated, and its mechanical properties were also evaluated. The results showed that under the influence of the high-entropy effect, a large amount of a (Fe, Co, Ni)-rich face-centered cubic solid solution formed and became the main component of the seam. On the other hand, only a small amount of Ti-based intermetallic compounds (IMCs) existed in the seam, ensuring a high-quality joint. The interfacial microstructure was affected by the brazing temperature because the reaction degree and high-entropy effect changed simultaneously, as did the distribution of IMCs in the matrix, which significantly affected the mechanical properties. The maximum shear strength reached 568 MPa when the joint was brazed at 1180 °C for 10 min. This study proposed a novel approach for connecting dissimilar metals, thus increasing the potential of EHEAs as fillers.