Hybrid manufacturing of Al2O3-FeCoCrNiMn interpenetrating phase composites by DLP printing and metal-assisted interfacial evolution

Al 2 O 3 -metal interpenetrating composites are attractive for protective structures, but conventional infiltration often produces interfaces dominated by mechanical interlocking, which restricts interfacial bonding and load transfer. In this study, an integrated manufacturing route was developed to fabricate Al 2 O 3 -FeCoCrNiMn high-entropy alloy (HEA) interpenetrating composites. An Al 2 O 3 -HEA auxetic honeycomb skeleton was first prepared by digital light processing (DLP) 3D printing. HEA slurry was subsequently introduced into the designed pores by gel casting, followed by integrated debinding and vacuum hot-press sintering. This dual HEA introduction strategy embeds HEA particles in the printed ceramic skeleton while filling the pores with HEA slurry, thereby promoting interfacial diffusion and the formation of a continuous ceramic-metal interpenetrating structure. HEA incorporation improved the densification of the Al 2 O 3 -based skeleton and facilitated the formation of a Cr-rich interfacial diffusion layer at the Al 2 O 3 /HEA interface. For the representative 20 wt% HEA composition, high-vacuum sintering yielded a compressive strength of 1218 MPa and a volumetric energy absorption of 7.68 MJ/m 3 . The route enables co-processing of architected alumina with a high-melting metallic phase while linking printability, densification, and interface development.