Formation of omega and Ti2Ni phases in a residual Ti-Ni-Ti multilayer between stainless steel and zirconia after bonding at 1173K

Abstract

Stainless steel (316L) and 8mol pct Y2O3-stabilized zirconia (8Y-ZrO2) were bonded using a Ti-Ni-Ti multilayer at 1173K (900 degrees C) for 1h. Cross-sectional transmission electron microscopy specimens were prepared by an innovative focused ion beam plus lift-out technique. In addition to acicular alpha-Ti, the dissolution of Fe, Cr, and Ni diffusing outwards from 316L into beta-Ti led to the precipitation of the omega (omega) phase with different variants in the residual Ti foil between 316L and Ni. The omega-phase was not found in the residual Ti foil between Ni and 8Y-ZrO2, while Ti2Ni precipitates were precipitated in some alpha-Ti grains owing to the exclusion of Ni from the beta-Ti.