Improving the mechanical properties of cermet composites is driven at the interface, where metallization and active brazing can be utilized. However, the incorporation of precipitates and solutes in the metal phase leads to degradation of the cermet’s functional properties. To overcome this, we propose introducing, in air, transition metal-aluminate phases to promote adhesion between metals and ceramics. To elucidate this interface, we explored the thermal and mechanical impact of YSZ cermets. Weibull analysis of Ni-YSZ exhibited a ~50% increase in modulus of rupture, when doped with nickel aluminate (NiAl2O4) and a clear resistance of metal migration on the ceramic at high temperatures with minimal degradation in electronic conduction. Comparably, for undoped Cu-YSZ, thermal cyclic variance gave evidence to interfacial degradation. When introducing copper aluminate (CuAl2O4) to Cu-3YSZ, thermal constraint of the cermet’s thermal expansion, suggests interfacial modifications between the ceramic and metal phases, preventing thermal degradation while preserving thermal conductivity.