EVALUATION OF FIBRE-MATRIX INTERFACIAL STRENGTH IN A SiC FIBRE-REINFORCED Ti-6A1-4V COMPOSITE

摘要

A high resolution depth sensing indentation instrument, developed at NRC, called the Nanomechanical Probe, was used to conduct fibre push-out (FPO) tests on a SiC fibre-reinforced Ti-6A1-4V composite, produced by a spray method. Samples were tested in the as-fabricated state, after heat treatment and after hot isostatic pressing (HIPing). In all cases, load-displacement plots obtained from the FPO tests showed an initial linear increase in the load with displacement which was followed by a sudden drop of the load. This drop was attributed to failure of the fibre-matrix interface and the start of sliding of the fibre out of the matrix. Scanning electron microscopic examination of the samples after the test showed tested fibres protruding from the sample as a result of sliding during the FPO test. The maximum load values, obtained before the sudden drop, were used in a model to calculate the fibre-matrix interfacial strength. The results indicated that the interfacial strength of the HIPed sample was more than five times higher than that of the as-fabricated sample. The heat treatment, on the other hand, was found to reduce the strength by a factor of two as compared to the as-fabricated material.