Powder Processing of AA 6061 Aluminium Metal Matrix Composites Using Hot Forging as Means of Consolidation

Abstract

The manufacture of bulk metal matrix composites (MMCs) by direct hot pressing of blended prealloyed powder (AA 6061) with 15 vol.-% of SiC particles (SiCp) and/or Saffil fibres, in an aluminium degassed can, is considered. Microstructure, mechanical properties, and wear resistance are compared with those of monolithic 6061 alloy and with selected examples from the literature. Good dispersion of reinforcement was achieved in the SiCp MMCs which, when heat treated to the T6 condition (solution treatment, quench, age), possessed 0·2% proof stresses of 400 MN m−2 with UTSs of ∼420 MN m−2 and elongations to failure of ∼2·5%. The Saffil and Saffil + SiCp MMCs had proof stresses of ∼350 MN m−2, UTSs of ∼380 MN m−2, elongations between 0·5 and 1·30%, and K Q values of ∼15 MN m−3/2. Pin on disc tests showed the sliding wear resistance of the SiCp MMC to be greatly superior to that of monolithic AA 6061 and also better than those of the Saffil and hybrid composites. PM/0673