DUAL-STAGE TERTIARY CREEP OF A CERAMIC-MATRIX COMPOSITE

The creep behaviour of an alumina fibre/silicon carbide matrix composi te has been studied. The creep curves are characterised by a short pri mary stage followed by one or two tertiary stages. The secondary regim e of this composite is limited to a single point. The occurrence of on e or two tertiary stages in the creep behaviour is discussed, and some theoretical considerations are invoked to explain this behaviour. Cre ep in this composite is controlled by two mechanisms, namely viscoplas tic creep of the alumina fibres and damage accumulation within the com posite. The two tertiary stages differ in the damage mechanisms occurr ing, the first one being related to fibre-matrix debonding only, where as successive fibre failure dominates in the second part. The second t ertiary regime occurs only at low creep stresses, for which a non-cata strophic rupture of the composite is observed. (C) 1998 Elsevier Scien ce S.A. All rights reserved.