Additive manufacturing (AM) of metal–cermet multimaterials presents a promising avenue for creating components that combine superior high-temperature strength, corrosion resistance, and toughness, which are crucial for extreme-environment applications. However, this potential is severely hampered by interfacial cracking caused by differential thermal contraction during sintering. To address this critical issue of interfacial stress stemming from the coefficient of thermal expansion (CTE) mismatch between NiFe 2 O 4 -based cermets and CuNi alloys, we develop a laminated strategy that integrates metal-phase distribution design with printing orientation control during material extrusion AM. This approach effectively mitigates sintering-induced stresses, enabling the fabrication of defect-free, functionally graded components. Our systematic investigation reveals that interfacial cracking in samples with flat interfaces intensifies with increasing metal layer thickness. In contrast, architecting curved interfaces promotes mechanical interlocking, thereby significantly enhancing interfacial bonding strength. Remarkably, vertically printed samples develop a characteristic serrated interfacial microstructure along the longitudinal section, the dimensions of which can be precisely tailored by adjusting the printing layer height. This microstructural feature plays a pivotal role in stress alleviation. Consequently, the optimized multimaterial component exhibits a superior bending strength, showing a remarkable 125% enhancement over the single-material cermet sample. This study provides new insights into mitigating sintering-mismatch stress in multimaterial systems via interfacial structure design and microarchitecture control, advancing high-performance metal–cermet multimaterials for extreme-environment applications. A layered 3D printing strategy, by architecting the spatial distribution of the metal phase and tailoring the printing orientation, successfully constructs curved interlocking microstructures at cermet-alloy interfaces during co-sintering. This design achieves a remarkable bending strength of 367.5 MPa—approximately 125% higher than its single cermet counterpart—while effectively suppressing delamination without the need for complex interface engineering or external reinforcement. The interlocked interface mechanically anchors the two phases, deflects propagating cracks, and leads to a synergistic combination of ceramic wear-resistance and alloy toughness. • A layered 3D printing strategy controls metal phase placement and orientation to reduce stress in cermet-alloy co-sintering. • The vertical printing strategy creates a unique zigzag microstructure at the interface, enabling mechanical interlocking. • The multimaterial sample reached 367.5 MPa in bending strength, 125% higher than monolithic cermet.
Ouyang et al. (Sun,) studied this question.