Enhanced strengthening of Al-SiC nanocomposites containing a uniform dispersion of dense nanoparticles fabricated by a hybrid accumulative roll-bonding process

摘要

Al matrix nanocomposites reinforced by SiC nanoparticles were fabricated by a hybrid accumulative roll-bonding (HARB) process with ultrahigh rolling cycles. Experimental results showed that a highly uniform dispersion of SiC nanoparticles with a high volume fraction (up to 20%) in Al matrix can be achieved by HARB. The grains of Al matrix were refined into the size range of 180-740 nm, depending on the volume fraction of SiC. The as-prepared AL-SiC nanocomposites exhibited remarkably enhanced microhardness (maximum: 216 HV) and tensile strength (maximum: 603 MPa), both approximately 9 times those of the unreinforced matrix. The as-prepared Al-SiC nanocomposites also showed an excellent combination of strength and ductility as compared with other Al matrix composites. The enhanced strengthening of the nanocomposites can be attributed to the efficient contributions of various strengthening mechanisms owing to the uniform dispersion of dense SiC nanoparticles. The distinct strengthening effect due to coefficient of thermal expansion mismatch was evidenced and discussed.