Far-from-Equilibrium Processing of ZrO_2(3Y_2O_3)-Al_2O_3 Nanocomposites

摘要

Nanocomposites of yttria-stabilized zirconia (YSZ), containing 20 and 40 wt% alumina, were prepared by a two-step process: (1) fine-particle aggregates of the constituent phases are melted and homogenized in a high enthalpy plasma, prior to rapid quenching in water to obtain a far-from-equilibrium metastable powder; and (2) the metastable powder is then consolidated by Hot Isostatic Pressing (HIP), under conditions designed to ensure the formation a nanocomposite by controlling the metastable-to-stable phase transformation during sintering. In both compositions, the resulting nanocomposites have completely uniform structures, comprising 27 and 50 vol% of α-Al_2O_3 in a tetragonal YSZ matrix phase. The decomposition of these metastable powders may be controlled by varying the HIP processing temperature.