Transmission electron microscope investigation of the interface between titanium and zirconia

Abstract

The interfaces between 3-mol%-yttria-partially-stabilized zirconia and commercially pure titanium after reaction at 1750 degrees C were analyzed with a scanning electron microscope and an analytical transmission microscope. Zirconia was reduced to oxygen-deficient zirconia (ZrO2-x) with an O/Zr ratio as low as 1.53, causing the evolution of oxygen. Part of the oxygen could accumulate at grain boundaries, the remainder being dissolved in titanium as alpha-Ti(O). An ordered titanium suboxide (Ti3O) could be formed from a solid solution of alpha-Ti(O) during cooling. A fine crystalline ZrO2-x phase (O/Zr approximate to 2) was also found along with alpha-Zr near the interface on the zirconia side. The alpha-Zr was twinned with one of the twin planes being indexed as {10 (1) over bar 2}. The yttria stabilizer was excluded from zirconia as the reaction was progressing, existing as oxygen-deficient yttria, Extensive dissolution of zirconia in titanium gave rise to the formation of alpha-Ti(Zr,O) solid solution. On cooling, lamellae of Ti2ZrO precipitated from alpha-Ti(Zr,O) with an orientation relationship of {110}(Ti2Zro)//{100}(alpha-Ti) and [111](Ti2ZrO)//[011](alpha-Ti).