Does the stacking fault energy affect dislocation multiplication?

This paper investigates the interdependence of the stacking fault energy (SFE) and the stress required for dislocation multiplication. For this purpose copper-aluminum (Cu-Al) alloys with varying Al content are investigated by spherical nanoindentation. The load-displacement curve shows a characteristic pop-in, which is interpreted as elastic-plastic transition and correlated to the dislocation source nucleation and/or activation stress. The statistical analysis of the pop-in behaviour documents a strong dependence of the maximum shear stress beneath the indenter on the Al content, which cannot be explained by a variation in shear modulus. Instead, the pop-in stress clearly increases with increasing stacking fault energy.