Young’s modulus of Al/SiCP/MgAl2O4 composites with different particle size distribution of reinforcements

Abstract

The effect of particle size distribution of SiC particulate reinforcements coated with colloidal SiO2 on Young ́s modulus of Al/SiCp/MgAl2O4 composites fabricated by reactive infiltration was investigated. Composites were prepared from porous preforms of silica-coated α- SiC powders of 10, 54, 86, and 146 μm, 0.6 volume fraction of reinforcements and particle size distribution from monomodal to cuatrimodal. Infiltration tests with the alloy Al-13.3Mg-1.8Si (wt. %) were carried out in Ar→N2 atmosphere at 1100oC for 60 min. The composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition to density and residual porosity measurements, Young ́s modulus was evaluated by ultrasonic techniques. Results show that with increase in particles size distribution, residual porosity decreases and density and Young ́s modulus of the composites are improved, the latter from 185.39 ±3.6 to 201.93 ±2.3 GPa. This is attributed to the increased metal-ceramic interfaces and to an enhanced matrix-reinforcement load transmission.