Effect of Ceramic Particle Size on Mechanical Behavior of Al Composites.

Abstract

Mechanical behavior of 7xxx series Al metal matrix composite (MMC) powders with different Al2O3 particle size were investigated. Ceramic content of starting powder whose ceramic particle size was 20 and 100μm was 10 wt.%. And 7xxx Al blended elemental powder was used for comparison. The powders were uniaxially cold-compacted and sintered at 620oC in a dry N2 atmosphere for 60min. Subsequently, sintered parts were solution treated at 475oC and aged at 175oC. To reveal the effect of Al2O3 particle size on the tensile properties of composites, tensile test was conducted with constant strain rate of 1×10-3/s using sub-size rectangular tension test specimen. As a result, it showed the intergranullar fracture which was caused by the delamination between matrix and reinforcement particles. Additionally, it was shown that the delamination caused by the differences in thermal expansion coefficient during heat treatment.