MONITORING LOCALIZED DEFORMATION OF PSEUDOELASTIC NITI SUBJECTED TO UNIAXIAL LOADING

摘要

Localization of transformation/deformation is frequently observed in pseudoelastic NiTi subjected to uniaxial tension. As this deformation mode affects the macroscopic mechanical behavior of specimens and components, there is a need for detailed experimental investigations on formation and growth of martensitic transformation bands. Here, we present experimental results of crosshead-displacement controlled tensile experiments on pseudoelastic NiTi wires and ribbons. The nucleation and propagation of transformation bands in these uniaxial experiments is documented in-situ by three different methods, (1) infrared thermal imaging, (2) optical stereo microscopy, and (3) alternating current potential drop measurements. Particularly the last method represents a novel approach for the characterization of localized transformation events in shape memory alloys. We discuss how the complementary information obtained by the different experimental techniques can be combined in detailed in-situ investigations of localization phenomena in NiTi.