High-entropy alloy buffering for defect-free additively manufactured multi-materials with stable mechanical properties

초록

Directed energy deposition enables the fabrication of compositionally tailored multi-material structures, but direct deposition of Inconel 718/SS316L multi-materials is prone to cracking because of the formation of deleterious brittle phases at the dissimilar interface. Here, we introduce an equiatomic CoCrFeMnNi high-entropy alloy buffer layer between SS316L and Inconel 718 to mitigate crack formation in additively manufactured multi-materials. Microstructural characterization and Scheil-Gulliver solidification simulations show that the HEA buffer layer reduces direct compositional mixing of SS316L and Inconel 718, suppressing local compositions susceptible to brittle Laves-phase formation and reducing the thermal stress on the SS316L region. As a result, the HEA-buffered multi-material prevents interfacial cracking, contributes to stable tensile deformation, and improves repeatability compared with the unbuffered SS316L/Inconel 718 joint. These findings demonstrate that HEA buffer layers can serve as compositionally tolerant interlayers for robust additive manufacturing of dissimilar alloy systems.

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