Transverse tensile behaviour of fibre reinforced titanium metal matrix composites

摘要

Four Ti MMCs have been tested in transverse tension, at ambient temperature and 600 degrees C. Generally, mechanical properties are reduced compared to monolithic Ti alloys. Transverse Young's modulus is, however, higher than in monolithic alloys, as a result of constraint of the matrix by the fibres. MMC proportional limits are associated with the onset of interfacial failure. Fibre coating cracking and longitudinal fibre splitting may also contribute to MMC yield and the associated acoustic emission peak. The fibre/matrix 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 brittle manner. This causes poor transverse tensile strength and failure strain in this MMC. A model to predict the MMC proportional limit, previously proposed by Jansson 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 predict the transverse tensile strength is acceptably accurate provided that the area fraction of matrix appearing on fracture surfaces is accurately determined. (C) 1998 Kluwer Academic Publishers. [References: 48]