Microstructure and strengthening of metal matrix composites

The effects of composite microstructure (e.g. particle size and volume fraction) on the mechanical properties of 2080 Al matrix composites with SiC particulates are considered. Finite element calculations on unit cell representations are compared to tensile measurements. For fine particles, good agreement is obtained for inclusion volume fractions as large as 30%. Coarse particle materials show evidence of particle cracking, which degrades the modulus and yield stress. In a new computational approach, the unit cell of a cracked particle and surrounding matrix is embedded in an effective medium with properties of a composite with intact particles. By appropriate choice of the portion of cracked particles, experiments on materials with a broad distribution of particle sizes are reproduced by the model calculations.