The high temperature behaviour of long fibre reinforced titanium under transverse loading

Isothermal and thermal cycling creep tests have been performed on titanium matrix composites reinforced with continuous SiC fibres under transverse loading. Isothermal results have shown that the creep exponent of the reinforced matrix is much lower than that of the unreinforced matrix. Influence of thermal cycling parameters is examined and comparison is made with the results of isothermal tests. It is demonstrated that stress relaxation in the matrix and interfacial damage play a key role. It is also shown that post-fabrication heat treatment greatly improves the high temperature mechanical properties of the composites. After a detailed analysis of the interface, the different mechanisms of damage have been identified. Evidence is given that the properties of the carbon and TiB2 layers, originally present at the fibre surface, are responsible for the low resistance to damage of the as-fabricated materials under transverse loading.