Cu, Cu-2.2Al and Cu-4.5Al with stacking-fault energies of 78, 35 and 7mJ/m2, respectively, were processed by cold-rolling at liquid-nitrogen temperatures (77K) after hot-rolling. X-ray diffraction measurements indicated that a decrease in stacking-fault energy led to a decrease in crystallite size but an increase in microstrain, dislocation and twin density of cold-rolled samples. Tensile tests at room temperature indicated that, as the stacking-fault energy decreased, the strength and ductility increased. The results indicated that decreasing stacking-fault energy was an optimum method for improving the ductility, without loss of strength.

Effect of Stacking Fault Energy on Mechanical Properties of Ultrafine-Grain Cu and Cu-Al Alloy Processed by Cold-Rolling. X.Y.San, X.G.Liang, L.P.Cheng, L.Shen, X.K.Zhu: Transactions of Nonferrous Metals Society of China, 2012, 22[4], 819-24

           Figure 3

 Stacking-Fault Energy of Cu-Al Alloys

(Closed symbols: present work, open circles: previous work)