Effect of dilution on fabricated functionally graded materials compositions: Modelling and mitigation strategies validated using the Ni-, Fe-, Cu- alloy system

Additive manufacturing (AM) can be used to fabricate functionally graded materials (FGMs) in which composition, and therefore properties, vary spatially within a component. A practical consideration for FGM fabrication is the effects of dilution. In the gradient region of vertically graded FGMs, dilution from the previous layer with a different composition from that being newly deposited can result in the composition of the newly solidified layer deviating from the feedstock composition from the nozzles. In this study, a dilution model for multi-layer FGM samples is proposed and validated experimentally with an Inconel625 (IN625)-Monel400 FGM sample. Factors that affect the deviation from the designed compositional path are discussed and methods for mitigating dilution effects to produce designed path are provided and experimentally demonstrated in a stainless steel 316 L (SS316L)-50/50 wt% SS316L/Ni-Monel400 FGM sample, aiding in precise production of the designed FGM path.