Interfacial Characterization of Selective Laser Melting of a SS316L/NiTi Multi-Material with a High-Entropy Alloy Interlayer

Some multi-materials produced via SLM and containing 316L steel may exhibit defects and cracks in the interfacial zone. There is a lack of research on 316L/NiTi multi-materials with an interlayer produced via SLM. This study aims to investigate the influence of a high-entropy alloy (HEA)-CoCrFeNiMn interlayer on the defects' formation, microstructure, phase, and chemical compositions, as well as the hardness of the interfacial zone. It was concluded that using of high-entropy alloy as an interlayer in the production of 316L/HEA/NiTi multi-material via SLM is questionable, since numerous cracks and limited pores occurred in the HEA/NiTi interfacial zone. The interfacial zone has an average size of 100-200 mu m. Microstructure studies indicate that island macrosegregation is formed in the interfacial zone. The analysis of phase, chemical composition, and hardness demonstrates that a small amount of FeTi may form in the island macrosegregation. The increase in iron content in this area could be the reason for this. The interfacial zone has a microhardness of about 430 HV, and in the island macrosegregation, the microhardness increases to about 550 HV. Further research could involve an in-depth analysis of the phase and chemical composition, as well as examining other metals and alloys as interlayers.