Observation and quantitative analysis of damage caused by creep in an A1 A359/SiCP composite

Damage introduced by creep at 270 °C to an A359 aluminium alloy matrix/20vol.% SiC particle composite has been studied by scanning electron micrography, using backscattered electron images. Debonding at matrix/particle interfaces and cracks within SiC particles are revealed by this method. An image analysis technique has been developed to distinguish between and quantify damage in the form of matrix voiding, particle cracking and matrix/particle debonding. Damage is analyzed statistically by observing a sufficient number of damage events. It is found that larger particles are more prone to damage. Particles smaller than 4 μm in diameter are not damaged. Debonding and cracking occur predominantly perpendicular to the tensile direction. Damage appears after a certain amount of creep strain is introduced and the rate of damage accumulation is found to accelerate with increasing levels of damage.