Transverse tensile behaviour of fibre reinforced titanium metal matrix composites

Four Ti MMCs have been tested in transverse tension, at ambient temperature and 600 degrees C. Generally, mechanical properties are reduced compared t o monolithic Ti alloys. Transverse Young's modulus is, however, higher than in monolithic alloys, as a result of constraint of the matrix by the fibre s. MMC proportional limits are associated with the onset of interfacial failur e. Fibre coating cracking and longitudinal fibre splitting may also contrib ute to MMC yield and the associated acoustic emission peak. The fibre/matri x interface in IMI 834/SM1140+ appears to be weaker than in the other MMCs, resulting in a lower proportional limit and less acoustic emission. Final failure of the MMCs is generally via ductile shearing of matrix ligaments. The exception to this is IMI 834/SM1140+ in which the matrix fails in a bri ttle manner. This causes poor transverse tensile strength and failure strai n in this MMC. A model to predict the MMC proportional limit, previously proposed by Janss on et al., has been modified to take account of the tensile strength of the fibre/matrix interface. The model previously used by Jansson et al. to pre dict the transverse tensile strength is acceptably accurate provided that t he area fraction of matrix appearing on fracture surfaces is accurately det ermined. (C) 1998 Kluwer Academic Publishers.