Interfacial Bonding in Multi-material Structures made by Additive Manufacturing

Tuesday, October 1, 2024: 9:20 AM
22 (Huntington Convention Center)
Mr. Wei Zhou , Nanyang Technological University (NTU), Singapore, 440, Singapore
Development of additive manufacturing technology has made it possible to produce multi-material structures with tailor-made properties at specific sites. A case study is presented of stainless steel 316L/nickel-based superalloy Inconel 718 structure made by laser directed energy deposition (DED). Compositional segregation was observed to occur at the interface, resulting in microcracking on the side of Inconel 718. To mitigate the problems, it is essential to minimize the dilution during the laser DED process. An example is given to demonstrate the possibility of achieving almost zero dilution using a new method invented by the author. The method is termed as “laser additive brazing” and it is a type of laser DED process but differs from the usual process in that the laser is used to melt the powders above the substrate and the melt temperature is carefully controlled through adjusting the distance between the melt zone and the substrate. Very low dilution might lead to poor interfacial bonding for some materials, but the problem can be overcome through ultrafast laser texturing of the substrate. The concept is demonstrated using examples of laser DED of W/Cu structure and ebeam deposition of γ-TiAl on Ti–6Al–4V substrate.