Dissimilar fabrication of the TC4/Ni60 bimetallic structure by laser melting deposition using a V/Cu transition bilayer

Abstract

The bonding of Ti and Ni alloys to manufacture high-quality bimetallic structures represents an optimal integration strategy for fully leveraging their superior performance. However, the metallurgical bonding between TC4 and Ni60 dissimilar metals is extremely challenging due to the formation of TiNi, TiC and TiFe brittle intermetallic compounds and the differences in thermophysical properties. To address this issue, this paper presents a solution based on the compatibility of elemental components. A V/Cu transition bilayer was designed to achieve defect-free bonding between TC4 and Ni60 by laser melting deposition. The microstructure of the TC4/Ni60 bimetallic structure was analyzed by SEM, XRD and EBSD to evaluate its feasibility. The results indicate that the generation of brittle intermetallic compound phases was reduced to a certain extent when a V/Cu transition bilayer was employed, thus preventing cracking and peeling of the TC4 substrate and Ni60 cladding layer. Additionally, the mechanical properties of the bimetallic structure were evaluated through micro-shear tests and tensile tests. The micro-shear test results indicate that the weakest layer of the bimetallic structure is the Cu transition layer with a shear strength of 183.0 ± 108.8 MPa and an indentation rate of 8.25 ± 3.3 %. The room temperature tensile results demonstrate that the developed bimetallic structure fractured at the Cu/Ni60 interface, exhibiting a tensile strength of 286.3 ± 54.1 MPa and an elongation of 6.3 ± 0.5 %. The expected research can provide valuable references for improving the mechanical properties of TiNi dissimilar bimetallic structures produced by laser melting deposition.