TENSILE DEFORMATION AND FRACTURE-TOUGHNESS OF 2014+15 VOL PCT SIC PARTICULATE COMPOSITE

Tensile tests and fracture toughness experiments were conducted on 2014 aluminum alloy with 15 vol pct SiC particulate in a stage which fit within a scanning electron microscope. Strains associated with tensile deformation and the transition from slow to rapid crack growth were determined using the stereoimaging technique. Overall tensile elongations were measured at 1.6 to 2.4 pct, while localized strains were up to approximately 50 pct but dependend on the dispersion of SiC particles. Measured fracture toughness values ranged from 18.7 to 29.5 MPa square-root m. Fractography revealed the virtual absence of dimpled rupture on both types of specimens. The fracture toughness values measured could be accounted for by computing the work done in forming new crack surfaces. To do this, the strain gradients determined during the tests were used in a previously developed model. Matrix ductility and particle dispersion are identified as the factors controlling toughness.