A novel powder metallurgy strategy for fabricating copper foam sandwiches with metallurgical bonding interfaces

This study introduces a powder metallurgy-based strategy to fabricate copper foam sandwiches (CFSs) with metallurgical bonding interfaces, thereby overcoming the interfacial limitations of conventional riveted or brazed CFSs. A panel-core-panel structure was constructed using copper powder and needle-shaped carbamide, followed by pressing and gradient sintering, which simultaneously enabled porous core formation and interfacial bonding. SEM-EDS, XRD and μ -CT analyses confirmed continuous Cu distribution across the CFS interface via atomic diffusion. Mechanical testing showed that the CFS exhibited a compressive strength of 24.8 MPa (comparable to that of single-layer copper foam, 25.2 MPa) and a shear strength of 43.2 MPa, which was approximately ten times higher than that of single-layer copper foam (4.1 MPa) and over thirteen times greater than that of brazed CFS (3.2 MPa). This improvement results from reduced interfacial resistance due to metallurgical bonding. The proposed strategy achieves structural-mechanical synergy and offers a scalable solution for developing high-strength metal foam sandwich structures.