A new strategy for high-strength joining of dissimilar materials

Abstract

A new strategy that utilizes the multicomponent amorphous alloy as the filler metal to join the hard-to-weld dissimilar materials was proposed. The coexistence of multiple principal elements 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 bulky directional intermetallic compounds. To give a theoretical analysis of the phase evolution of the joint and verify the feasibility of this strategy, vacuum brazing of TiAl- and Ni-based alloys with a high-entropy amorphous filler Ti20Zr20Hf20Cu20Ni20 as the filler metal was performed and the phase evolution was analyzed from the perspective of kinetics and thermodynamics. The experimental result showed that a circular solid solution phases firstly formed at high temperature, and fine phases were then precipitated from the solid solutions accompanied by a precipitation strengthening effect to the joint as the temperature decreased. The shear tests showed that a maximum shear strength of 319 MPa can be obtained, and the multiple principal elements filler metal proved to be a promising and feasible approach to solve the difficult joining of hard-to-weld dissimilar alloys.