Breaking the strength-ductility trade-off in additively manufactured aluminum alloys through grain structure control by duplex nucleation

摘要

Achieving a homogeneous equiaxed grain structure and breaking the strength-ductility trade-off in ad-ditively manufactured aluminum alloys is a great challenge. In this paper, we propose a novel duplex nucleation mechanism that combines ex situ TiB2 and in situ Al3Ti for controlling the grain structure of additively manufactured AlCuMgTi-TiB2 composites. We conducted thermodynamic calculations and phase-field simulations to elucidate the duplex nucleation-based grain structure control. The Al3Ti-coated TiB2 inoculant system formed via duplex nucleation during solidification enabled the formation of a ho-mogeneous ultrafine equiaxed microstructure in both the as-fabricated and heat-treated states. Different from the AlCuMgTi alloy, the TiB2-reinforced AlCuMgTi composites produced via laser powder bed fusion were amenable to the simultaneous enhancement of strength and ductility. The proposed alloy design ap-proach and duplex nucleation mechanism can guide the tailoring of the microstructure and mechanical properties of additively manufactured aluminum parts.

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