Microstructural evolution and formation mechanism of the interface between titanium and zirconia annealed at 1550°C

The diffusional reaction between titanium and zirconia was carried out isothermally at 1550 degrees C in argon. The distinct reaction layers in the reaction-affected zone between Ti and ZrO2 were investigated using analytical scanning electron microscopy, analytical transmission electron microscopy, and electron probe microanalyses. In the metal side, there existed five reaction layers in a sequence of alpha-Ti(O), Ti2ZrO+alpha-Ti(O, Zr), Ti2ZrO+alpha-Ti(O, Zr)+beta'-Ti (O, Zr), alpha-Ti (O, Zr)+beta'-Ti (O, Zr), and beta'-Ti (Zr, O) after cooling. In the zirconia side, two reaction layers were found: near the original interface, beta'-Ti coexisted with fine spherical c-ZrO2-x and Chinese-script-like c-ZrO2-x, which dissolved a significant amount of Y2O3 in solid solution; further away from the original interface, the coarsened intergranular alpha-Zr was excluded from metastable ZrO2-x, resulting in the lenticular t-ZrO2-x and ordered c-ZrO2-x. An attempt was made to determine and propose the microstructural evolution and formation mechanism of the reaction layers between titanium and zirconia isothermally annealed at 1550 degrees C.