Cu–xGe alloys were prepared by forging at liquid-nitrogen temperatures and their mechanical properties were systematically investigated. The results indicated that the microhardness, strength and uniform elongation of Cu–xGe alloys were simultaneously improved by lowering the stacking-fault energy. The stacking-fault energies for 3N9 Cu and 0.1Ge, 5.7Ge and 9.0at%Ge alloys were 78, 54, 15 and 8mJ/m2, respectively. X-ray diffraction measurements revealed that a reduction in stacking-fault energy led to a decrease in grain size and to an increase in dislocation density, twin density and microstrain for the cryogenically forged samples. It was thus demonstrated that a high strength and excellent ductility could be simultaneously achieved by lowering the stacking-fault energy of the metals.

Simultaneously Enhanced Strength and Ductility of Cu–xGe Alloys through Manipulating the Stacking Fault Energy. Y.L.Gong, C.E.Wen, Y.C.Li, X.X.Wu, L.P.Cheng, X.C.Han, X.K.Zhu: Materials Science and Engineering A, 2013, 569, 144-9