Interfacial characterization and mechanical properties of additively manufactured IN718/CoNiCrAlY laminate

IN718/CoNiCrAlY multi-material laminates were prepared using laser powder bed fusion. The microstructure, phase composition, grain orientation, microhardness, and tensile properties of the multi-material were investigated. The results showed that the interface between IN718 and CoNiCrAlY was compact without cracks and had good metallurgical bonding. The interface was mainly composed of the gamma-Ni(Co, Cr) solid solution matrix phase, beta-NiAl intermetallic compound, and some eta-Ni3Al0.5Nb0.5 precipitated phase. The microstructure of the interface along the building direction consisted of columnar dendrites with a strong (100) < 001 > cubic texture. A higher kernel average misorientation value was observed at the interface, indicating stress concentration, which was attributed to the intrinsic stress caused by the lattice differences between the two materials. The microhardness increased first and then decreased from IN718 to CoNiCrAlY along the building direction, and the hardness in the transition region was the highest (367.0 & PLUSMN; 3.7 HV). The ultimate tensile strength of IN718/CoNiCrAlY joint was 871.4 & PLUSMN; 13.0 MPa, which was lower than that of single IN718 and single CoNiCrAlY. Fracture analysis revealed that the multi-material specimen fractured in the transition region, and the fracture morphology was a mixed mode of cleavage fracture and micropore aggregation fracture.