Abstract

The internal crystallisation method (ICM) allows producing bundles containing hundreds and thousands of the fibres of a limited length. It is shown in the present paper that ICM can be used to produce fibres composed of a sapphire matrix and inclusions of calcium hexaaluminate. The fabrication of such composite fibres is described in the present paper. An effect of the calcium hexaaluminate inclusions in sapphire fibres is evaluated by testing model composites with brittle molybdenum matrices. The critical stress intensity factors of composite-fibre/molybdenum-matrix specimens are higher than those of specimens reinforced with sapphire fibres. The model specimens reveal non-linear stress/strain behaviour. The results of this work show the effectiveness of composite fibres as a reinforcement for brittle matrices.

Highlights

  • It is well known that a brittle-matrix/brittle-fibre composite can reveal quasi-plastic behaviour determined by the crack arrest by a “weak” fibre/matrix interface [1,2]

  • Only preliminary on the microstructure of the composite fibres ahas study the crystallisation mechanisms of the (1-α)Alshould melts in the channels of to thea beenofobtained because a study of the microstructure be, first of all, complementary

  • Oxide fibres composed of sapphire and calcium aluminate inclusions by using

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Summary

Introduction

It is well known that a brittle-matrix/brittle-fibre composite can reveal quasi-plastic behaviour determined by the crack arrest by a “weak” fibre/matrix interface [1,2]. Groeth [9], Laser Heated Pedestal Growth [10], and μ-pulling down [11] Fibres produced by these methods are characterised by a nearly ideal microstructure, but they are too expensive to be used as reinforcement for structural composites [6]. The internal crystallisation method (ICM) to produce single crystalline fibres, which is based on the crystallisation of oxides in cylindrical channels of an auxiliary matrix, is characterised by the much higher a productivity rate than is characteristic for the traditional methods, which makes ICM-fibres suitable for structural applications. ICM is used to obtain fibres composed of a strong sapphire strong sapphire matrix and inclusions of calcium hexaaluminate. An effect of the CA6 inclusions in sapphire fibres is evaluated by fibres is evaluated by testing model composites with brittle molybdenum matrices.

Fabrication of Composite Fibres
A Scanning
Ca and
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Schematicofofaaspecimen specimen with
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Conclusions
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