On the acoustic properties and plastic flow stages of deforming Al polycrystals

During extension tests of Al polycrystals, in situ measurement of ultrasoni c wave velocity (UWV) was carried out for the plastically deforming specime ns. UWV has been found to depend on the plastic strain or acting stress of plastic flow. The complicated form of these dependencies is discussed in th e context of the concept of evolution of lattice defects. The multistage na ture of the plastic flow curve is shown to be associated with UWV. This all ows plastic flow stages to be recognized with a higher degree of certainty. Thus, the Linear stage of work hardening has been separated for Al polycry stals by the procedure of UWV measurement and certain peculiarities of plas tic strains localization as associated with UWV variation have been investi gated. (C) 2000 Elsevier Science B.V. All rights reserved.