Experimental investigations on kinetics of Portevin–Le Chatelier effect in Al–4 wt.%Cu alloys

By employing the dynamic digital speckle pattern interferometry (DSPI) technology, the spatial kinematics features of Portevin–Le Chatelier (PLC) bands are vividly shown in terms of correlation fringe patterns. In this paper, three types of representative serrated flow on stress–time curves, combining with the position–time plots for the propagating PLC bands, have clearly classified the three types of PLC effect. Effect of strain and applied strain rates to the amplitudes of serrated stress drops is investigated and qualitatively interpreted via dynamic strain aging (DSA) mechanism. Evolution of the propagation velocity for type A and B bands versus strain and applied strain rate is also discussed, and is in good accordance with accepted previous work. Moreover, we note that the spatial correlation of PLC bands will diminish with decreasing specimen thickness.