Investigation into fracture mechanisms of, and the effect of stretch-straightening on an extruded metal-matrix composite
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A study has been made on samples of an extruded metal-matrix composite with an aluminium alloy (2124) matrix reinforced by 17.8% silicon carbide particles. Samples were straightened (plastically stretched) before performing tensile and compact tension tests. Fractographic analysis was affected using SEM analysis on single and matching faces. It was found that the ultimate tensile strength in the transverse direction decreased substantially (∼45 MPa) on stretching and that the fracture toughness was influenced by the quenching rate. Further, the longitudinal and transverse ductilities were found to decrease and increase, respectively, with increasing plastic stretch. The SEM analysis supported a fracture mechanism where particles either fractured or decohered ahead of the crack tip with ductile failure of the matrix between the crack tip and the damaged particles.
KeywordsCarbide Tensile Strength Ductility Aluminium Alloy Fracture Toughness
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