Formation of point defect clusters during the first cycles of copper fatigue

Abstract

The variation of point defect cluster density during the first cycles of copper fatigue has been studied by means of transmission electron microscopy. The strain amplitude, the total accumulated plastic strain, and the peak stress reached in the fatigue test are related to the cluster density. To compare with the fatigued specimens, the cluster density has also been measured in a tensile strained specimen. It has been found that the point defect clusters are formed at a high rate from the start of the fatigue test and their number tends to a saturation value. It has also been observed that the stress saturates before the stable value of the number of defects is reached.