Microstructure and properties of Al2O3-Al5Y3O12 fibres produced by an internal crystallization route

The fibres produced by the internal crystallization method can now be used in a variety of metal, intermetallic and ceramic matrices. The microstructu re of the Al2O3-Al5Y3O12 eutectic fibres produced by an internal crystalliz ation route varies with varia tions of initial melt composition and crystal lization conditions. Deviation of the composition from the eutectic point y ields formation of dendrites in the microstructure. The eutectic microstruc ture of the fibres appears to be characterized by a rather large disorienta tion. Qualitative correlation between the failure stress of a fibre and the appearance of the fibre surface is revealed. Coating the fibres with a sil icon oxy-carbide layer enhances the fibre strength, certainly as a conseque nce of the healing of defects. Strength characteristics of the fibres can b e widely controlled by changing fabrication parameters as well as by the ap plication of coatings. (C) 1999 Elsevier Science Ltd, All rights reserved.