Acoustic emission was investigated in tensile-strained model Cu-Ge alloys with germanium concentrations of 0.1 to 9.0at%. The roles of various micro-structural factors in acoustic emission were considered, and the effects of solid-solution hardening and stacking-fault energy on the acoustic emission power spectra were clarified. It was shown that even a small (0.1at%) addition of Ge significantly changed the acoustic emission, whereas the dislocation acoustic emission mechanisms were similar in pure copper and its dilute alloys. It was argued that solution-hardening was the main factor governing the acoustic emission behaviour in dilute Cu-Ge solutions: resulting in an increase in lattice friction, a decrease in dislocation velocity and consequently a reduction in the acoustic emission energy. The acoustic emission technique showed that twinning occurred from the very early stages of plastic deformation, together with dislocation slip in copper alloys having germanium contents as high as 5.7at% and that the stacking-fault energy was 20mJ/m2 or lower. Each type of acoustic emission source, dislocation glide and twinning, produced distinct features in the acoustic emission power spectra and wave-forms.

Effect of Solid Solution Hardening and Stacking Fault Energy on Plastic Flow and Acoustic Emission in Cu-Ge Alloys. A.Vinogradov, D.L.Merson, V.Patlan, S.Hashimoto: Materials Science and Engineering A, 2003, 341[1-2], 57-73