Portevin-LeChatelier effect in strain and stress controlled tensile tests

The nucleation and propagation of Portevin-LeChatelier (PLC) deformation bands in Cu-15at.%Al have been studied by means of a novel multi-zone scanning laser extensometer providing information on the development of local strain along the main part of the specimen, in addition to the conventional measurement of stress serrations. By means of tensile tests with imposed constant strain rate independent data have been determined on propagation velocity, concentrated strain and width of the bands appearing in three different types of PLC-deformation. The tensile test machine has been softened to permit measurements with imposed constant stress rate. First results will be presented and compared to the strain-controlled ones on Cu-15at%Al. (C) 2002 Elsevier Science B.V. All rights reserved.