Dopant diffusion at the interface of TiO2‐MnO‐doped alumina/alumina layers in sintered laminates

Abstract Ceramic laminates were produced by thermal pressing of pure alumina (Al2O3) and TiO2‐MnO‐doped alumina (d‐Al2O3) tapes and subsequently sintered at temperatures ranging from 1100 to 1250°C. The diffusion of dopants through the interface was investigated by optical (OM), scanning electron (SEM) microscopy, nanoindentation, and energy‐dispersive X‐ray spectroscopy (EDS) together with scanning transmission electron microscopy. Temperature‐dependent dopant diffusion and porosity profiles were, respectively, observed investigating the microstructure. For d‐Al2O3, the average grain size, hardness, and Young's modulus were higher when compared to pure alumina, while the dopants diffusion zone presented intermediate values of these properties. The increase in sintering temperature resulted in higher values of hardness and Young's modulus in both layers. A further investigation showed a gradual decrease in grain size, hardness, and Young's modulus from the doped to the pure alumina layer, corresponding to a decreasing gradient in the dopants concentration in the Al2O3 layer with increasing distance from the interface. High concentrations of Mn and Ti were observed at triple points and grain boundaries, as well as within alumina grains.