Acoustic emission during plastic deformation of Pb-Sn alloys
The study explores acoustic emission under static loading of Pb-Sn alloys in a wide range of alloy element contents. The strain rate dependences of the acoustic emission count rate were plotted in mechanical tests. The obtained experimental data revealed a significant change in the type of recorded acoustic emission signals depending on the alloy structure, determined by the content of the alloy elements. With a low tin content, the recorded acoustic emission is generated by the dislocation fluxes localized at grain boundaries, with a large contribution of grain boundary sliding to plastic deformation. With an increase in the P-phase content, acoustic emission decreases sharply due to the formation of eutectic regions around the a-phase grains, which inhibit dislocation processes. For eutectic alloys, acoustic emission peaks were detected in the transition to intense plastic flow. Plastic deformation in this case was determined by the specific meso-structure of the alloy and occurred through the motion of individual eutectic colonies formed by alternating layers of the a and P phases. Strong acoustic emission activity in the hypereutectic region was observed with increasing tin content, due to increasing contribution of the P phase to acoustic emission. It was shown that qualitative differences in the meso-structure of Pb-Sn alloys manifested with changes in the element contents trigger various dominant mechanisms of plastic deformation, due to which the acoustic emission type changes markedly in the loaded alloy.