Interfacial reaction and microstructure investigation of CoCrFeNiMo medium-entropy alloys diffusion-bonded joints

In this study, vacuum diffusion bonding of non-equiatomic CoCrFeNiMo medium-entropy alloys (MEAs) was successfully achieved. The maximum tensile strength was found to be 597.13 MPa for the bonded joint prepared at 1050 °C. A nano-scale metal oxide film (Cr3O4) was formed at the welded joints which reduced the performance of the bonded joints. With the increase of bonding temperature, Cr3O4 gradually decreased, and the metal oxide film was broken and disappeared at 1050 °C due to diffusion of O elements to the substrate.