Crystallographically aligned metal–oxide composite made by reduction of a directionally solidified oxide–oxide eutectic

Abstract

Aligned metal–oxide composite materials have been grown from the melt by directional solidification at eutectic composition of several binary metal–oxide systems. The resulting microstructures consist of metallic fibres ∼1 µm in diameter imbedded in an oxide matrix^1,2. The occurrence of such fibrous structures, as opposed to lamellar structures, corresponds to eutectic compositions for which the volume fraction of the minor component is <30% (ref. 3). The work reported here presents a different route to the fabrication of aligned metal–oxide composites, making the production of fine–scale lamellar microstructures possible. The method consists of the chemical reduction of lamellar oxide–oxide eutectic structures in conditions of temperature and partial pressure of oxygen in which only one of the oxides is transformed to the corresponding metal. We show here how the method can be successfully applied to the preparation of aligned Ni–ZrO₂ lamellar structures.