The Portevin-le Chatelier Effect
At sufficiently low average strain rates in dead-weight quasi-static uniaxial stress experiments instabilities appear in the form of a series of successive steps superimposed upon the basic parabola of the large deformation. The first serious study of this phenomenon, in 1923, was that by Portevin and le Chatelier, after whom the phenomenon is now named. An example of this Portevin-le Chatelier effect may be seen in Fig. 7.1 in the present writer’s experiment 1219 for a 99.16% aluminum polycrystal. This experiment, shown in a σ2 vs ε plot in Fig. 3.3, is a dead-weight uniaxial tension measurement at a constant stress rate of 4.5 psi sec−1.
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