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Abstract The far-from-equilibrium solidification during additive manufacturing often creates large residual stresses that induce solid-state cracking. Here we present a strategy to suppress solid-state cracking in an additively manufactured AlCrFe2Ni2 high-entropy alloy via engineering phase transformation pathway. We investigate the solidification microstructures formed during laser powder-bed fusion and directed energy deposition, encompassing a broad range of cooling rates. At high cooling rates (104−106 K/s), we observe a single-phase BCC/B2 microstructure that is susceptible to solid-state cracking. At low cooling rates (102−104 K/s), FCC phase precipitates out from the BCC/B2 matrix, resulting in enhanced ductility (~10 %) and resistance to solid-state cracking. Site-specific residual stress/strain analysis reveals that the ductile FCC phase can largely accommodate residual stresses, a feature which helps relieve residual strains within the BCC/B2 phase to prevent cracking. Our work underscores the value of exploiting the toolbox of phase transformation pathway engineering for material design during additive manufacturing.

We used powder hot extrusion followed by annealing to fabricate a dual-phase AlCoCrFeNi2.1 eutectic high-entropy alloy consisting of both non-recrystallized and recrystallized grains with dense nano-sized precipitates arranged in heterogeneous structures. The resulting alloy exhibits superior tensile properties with a yield strength of ∼1.2 GPa, an ultimate tensile strength of ∼1.5 GPa, and a uniform elongation of ∼18%. Such multiscale microstructure results in exceptional strain hardening of the AlCoCrFeNi2.1 alloy by activating remarkable hetero-deformation induced (HDI) stresses. Our study provides an effective approach to fabricating high-performance structural materials via dual-phase heterogeneous microstructure design.