On the formation of necks in an Al13%Si eutectic alloy

Abstract

An Al-13%Si eutectic alloy was tested at an elevated temperature of 557 °C at constant strain rate. Marked deviations from uniform deformation occurred in the specimens tested at three different strain rates of 1 × 10 −5, 5 × 10 −4 and 1 × 10 −2 s −1 at elongations as low as approximately 50%. At a strain rate of 1 × 10 −2 s −1, a diffuse neck formed up to an elongation of 100%. Thereafter, the neck became sharp and catastrophic. At strain rates of 5 × 10 −4 and 1 × 10 −5 s −1, failure occurred by the formation and subsequent growth of sharp necks within the gauge length. These results are consistent with a genuine decrease in the value of the strain rate sensitivity index m with a decrease in strain rate.