Effect of temperature on the tensile properties of an as-cast aluminum alloy A319

The tensile properties of an as-cast A319 alloy were investigated as a function of temperature. It was found that the A319-Al alloy remained inherently brittle in the temperature range of −90 °C < T < 270 °C and the mechanical integrity was not satisfied as defined by the Considère criterion. Apparently, in this temperature range fracturing of brittle intermetallics, including Si particles is dominant. At T > 270 °C the mode of failure shifts to being essentially ductile by the development of numerous dimples. Under these conditions the development of critical stresses at matrix/particle interfaces needed for brittle fracture no longer occurs. Apparently, at these temperatures thermally activated processes lead to significant relaxation of stress incompatibilities at particle/matrix interfaces and results in appreciable plastic deformation within the matrix.