A new strategy of Al0.1CoCrFeNi high entropy alloys and Inconel 625 alloys joining technology

Abstract

A new strategy that utilizes the nano-multilayer foils with a high-entropy design as the filler metal to join the Al0.1CoCrFeNi and Inconel 625 alloy dissimilar materials was proposed, which provides theoretical and technical guidance for the development of aerospace technology and nuclear power. The coexistence of the nano-multilayer foils with a high-entropy design was envisaged to improve the role of mixing entropy and retard the atomic diffusion between the filler metal and base metals, inhibiting the formation of intermetallic compounds. To give a theoretical analysis of the phase evolution of the joint and verify the feasibility of this strategy, joining of the Al0.1CoCrFeNi and Inconel 625 alloy with Ni/Al nano-multilayer reaction foils, CrNi/CoFe nano-multilayer films, and Al foils as the filler was performed. The result showed that a defect-free brazing joint was formed and solid solution phase then occurred from solid solution reaction accompanied by solid solution strengthening effect to the joint as the temperature increased. The shear tests showed the highest shear strength (203.5 MPa) can be obtained. Additionally, prolonging the holding time and increasing brazing temperature made the shear strength of joint increase gradually and the fracture mechanism of the joint transformed from the inter-granular fracture to the trans-granular fracture. This effort offers a novel process for brazing Inconel 625 alloys and Al0.1CoCrFeNi, opening up a neo-field in the production of HEAs-related joints.