The axial compressive failure of titanium reinforced with silicon carbide monofilaments

Monofilament-reinforced titanium has been subjected to compressive loading, with a range of angles between the fibre axis and the loading direction. U nder axial loading, the failure stress is about 4 GPa, which is well bel6w levels predicted for kink band formation. It is proposed that compressive f ailure occurs under these circumstances by the crushing of individual fibre s. A model is proposed for prediction of the composite strength as controll ed by this mechanism. Observed strengths are consistent with monofilament c rushing stresses of about 8-10 GPa. Composites were also studied after a po st-consolidation heat treatment and with weak fibre-matrix interfacial bond ing. In both cases, slightly higher compressive strengths were recorded tha n for the standard material. These increases are attributed to an enhanced matrix yield stress and to a higher monofilament compressive strength, resp ectively. Under off-axis loading, strengths fell from about 4 GPa at low mi salignment angles to just above 1 GPa at an angle of 16 degrees. A transiti on occurs between fibre crushing at low angles and kink band formation at h igher angles. The transition range is around 3-4 degrees, which is consiste nt with model predictions. Microstructural studies confirmed that the expec ted failure modes were operative in these two regimes. (C) 1999 Acta Metall urgica Inc. Published by Elsevier Science Ltd. All rights reserved.