Transitional Phases at Ceramic–Metal Interfaces: Orthorhombic, Cubic, and Hexagonal Ti‐Si‐Cu‐N Compounds

Reaction products at the boundary between Si 3 N 4 and Ag‐Cu‐Ti braze alloy have been characterized by transmission electron microscopy. Beyond the TiN adjoining the Si 3 N 4 substrate is a continuous layer of a previously unreported, orthorhombic Ti‐Si‐Cu‐N compound. Evidence of additional cubic and hexagonal Ti‐Si‐Cu‐N phases is also found; these exist as isolated grains farther from the substrate. The cubic compound is probably an η‐type M 6 X phase of the sort observed at other ceramic‐metal interfaces. These “dilute ceramics,” in which metallic constituents dominate, are common transitional phases in ceramic‐metal systems.