Interface Engineering in FAST/SPS-Processed Multi-Material Metallic Systems: Bonding Mechanisms, Interfacial Reactions, and Mechanical Integrity

Abstract

Engineering components often require different properties in different regions, and a single material may not provide all of them. Reliable joining is important for refractory metal–steel, dissimilar superalloy, and Ti/Mg combinations. Field-assisted sintering technology/spark plasma sintering (FAST/SPS) combines pressure with rapid heating for direct joining and fabrication of interlayered and graded metallic structures in short cycles. This review evaluates factors affecting bond formation and mechanical integrity at FAST/SPS-processed metallic interfaces. Sufficient real contact is needed for load transfer but does not alone ensure mechanical integrity. Surface oxides can restrict contact, while local deformation may increase contact area and disrupt oxide films. As contact develops, atomic transport and interfacial reactions may alter transition-region composition and phase morphology, affecting fracture paths. Interlayers may improve contact and limit undesirable reactions but can also create new interfaces and reaction regions. Compositional transitions, reaction regions, and local hardness indicate interface development, but assessing their mechanical significance requires mechanical testing and fracture analysis. Room-temperature performance alone does not define service behavior. Thermal cycling, high heat flux, electrical conditions, or corrosive environments may therefore require application-specific evaluation. Differences in materials, equipment, geometry, and test methods limit direct comparison. Processing windows should therefore be tailored to each material pair and interface architecture according to operating temperature, loading, functional requirements, and environmental exposure.

The authors' abstract, as published at the source. Metals, 2026 · DOI ↗