Extended dislocation nodes in αCu-Al solid solution were observed by transmission electron microscopy, and the stacking-fault energy was determined (figure 3). The specimens were annealed at 700C after deformation. The variation in stacking-fault energy with composition was measured. The energy for pure copper was estimated to be 46.4mJ/m2. Experiments were performed on Cu-15.9at%Al quenched from various temperatures in order to study the effect of short range order on the stacking-fault energy. The latter varied with the quenching temperature, and the results exhibited a good correspondence with electrical resistivity, hardness and specific heat measurements. The variation in stacking-fault energy with quenching temperature was interpreted as being due to short range order rather than quenching stresses.

The Influence of Solute Atoms on the Stacking Fault Energy in αCu-Al Alloys. Y.Tomokiyo, K.Kaku, T.Eguchi: Transactions of the Japan Institute of Metals, 1974, 15[1], 39-45