Single crystalline oxide fibres for heat-resistant composites

A brief review of the methods of fabrication of single crystalline oxide fibres is presented. It is shown that the internal crystallisation method (ICM), that is crystallisation of the fibres in continuous channels in an auxiliary matrix (molybdenum carcass), yields high-productivity rate, which provides a base for the development of fabrication technology of oxide fibres as reinforcement for composites for high and very high use temperatures. The method has been used to produce a family of fibres including sapphire, aluminium–yttrium garnet, mullite as well as some oxide eutectics. Microstructure, strength and high-temperature creep of the fibres are discussed with the emphasis on creep properties. Results of creep tests of composites with matrices based on TiAl, nickel superalloys and oxides are also presented. It is shown that special microstructure of composites with brittle matrices, intermetallic and oxides, yields quasi-ductile behaviour of the composites.