Plastic deformation and failure in A359 aluminum and an A359-SiC _p MMC under quasistatic and high-strain-rate tension

The deformation and failure (under quasistatic and dynamic tension) of an A359 aluminum alloy and an A359 aluminum alloy reinforced by 20 vol.% SiC particles have been investigated. Tensile strains are measured using the laser occlusive radius detector (LORD) and/or strain gauge in Kolsky bar tests, and using the LORD and/or clip extensometer in quasistatic tests. The influence of the rate of deformation on the tensile stress-strain curves and on the failure strains is determined for these heterogeneous materials. Both composite and matrix behave in a brittle manner with no necking before fracture, and the tensile failure strain is slightly reduced at high strain rates. The fracture surfaces and the microstructure of the tested specimens of each material are examined using scanning electron microscopy and optical microscopy. The tensile failure of the A359 matrix alloy and the composite are controlled by the microcracking of Si particles.