Effect of graphite and transition elements (Cu, Ni) on high temperature tensile behaviour of Al–Si Alloys

The high temperature tensile behaviour of Al–Si alloy and Al–Si alloy reinforced with graphite particulate was investigated. The composite was developed by stir casting method. Tensile behaviour of alloy and composite were studied at different temperatures from room temperature to 300 °C. It was found that the tensile strength of alloy and composites were decreasing with increase in temperature. It was further noticed that Al–Si alloy with graphite and transition elements was stronger than alloy. The % elongation of the alloy was more than that of composites. The fractographic observations of fracture surface was analysed by scanning electron microscopy to understand the fracture mechanisms. Fractography revealed that the fracture behaviour of alloy changed from cleavage mode at room temperature to complete ductile mode at high temperature.

► High temperature tensile studies up to 300 °C.
► Brittle to ductile failure mode transition takes place at a temperature of beyond 200 °C for alloy and for composites; mixed mode of fracture is observed beyond 200 °C.
► Strain hardening exponent value is decreased with increasing temperature.
► Ultimate tensile strength of composite is higher than that of alloy for all testing temperatures.