Bonding Strength and Its Enhancing Mechanism of CuCr/In718 Dissimilar Materials with Mortise and Tenon Structure Interface Manufactured by Laser-Based Direct Energy Deposition (DED-LB) Using Powder Feedstock

The interface bonding strength is challenging for CuCr and In718 dissimilar alloys fabricated by Laser-Based Direct Energy Deposition (DED-LB) using Powder Feedstock. Here, direct-bonded CuCr/In718 dissimilar materials (DMs) (direct-bonded specimen) and CuCr/In718 DMs with mortise and tenon structure interface (mortise-tenon specimen) were deposited by powder DED-LB. Owing to the alternating inter-track and inter-layer remelting, the defects were avoided, and the Cu elemental diffusion was obvious in the mortise-tenon specimen. Thereby, the better metallurgical bonding strength was achieved in the mortise-tenon specimen. The sandwich-shaped microstructure, including fine equiaxed and columnar grains, and the heterogeneous microstructure consisting of large columnar, short columnar, and fine equiaxed grains were formed in direct-bonded and mortise-tenon specimens, respectively. The formation mechanisms of these microstructures were unveiled, respectively. Besides, the shear strength of direct-bonded and mortise-tenon specimens was investigated. Owing to the mortise and tenon structure, the ultimate shear strength (USS) was increased by 47.18%. The synergistic enhancing mechanism of macroscopic interfacial morphology, microstructure, and elemental distribution on shear strength was revealed.