Ti2ZrO phases formed in the titanium and zirconia interface after reaction at 1550 degrees C

Abstract

Hot-pressed 3 mol% Y2O3 partially stabilized ZrO2 was reacted with titanium at 1550° C/30 min. The interface was characterized by analytical transmission microscopy (transmission electron microscopy/energy-dispersive spectroscopy). The lamellar and the spherical Ti2ZrO as well as the orthorhombic β'-Ti were found to exist in the titanium side after cooling down to room temperature. The crystal structures of the lamellar and the spherical Ti2ZrO were orthorhombic and hexagonal, respectively. On heating, the dissolution of a large amount of zirconium and oxygen into titanium gave rise to the metastably supersaturated disordered α-Ti(Zr, O) solid solution where two different Ti2ZrO phases subsequently precipitated, while the β-Ti coexisting with α-Ti at high temperatures was transformed to the orthorhombic β'-Ti during cooling. The spherical hexagonal Ti2ZrO was an ordered structure, with Zr and O occupying substitutional and interstitial sites, respectively. The orientation relations between oc-Ti and the lamellae orthorhombic Ti2ZrO were determined to be [0001](α-Ti)//[110](Ti2ZrO) and (10 (1) over bar0)(α-Ti)//(1 (1) over bar0)Ti2ZrO; meanwhile, those between the α-Ti and the spherical hexagonal Ti2ZrO were [0001](α-Ti)//[0001](Ti2ZrO) and (10 (1) over bar0)(α-Ti)//(10 (1) over bar0)(Ti2ZrO).