Austenitic—martensitic interface damping measured in shape memory alloys by a cyclic tensile machine

Abstract

A tensile machine has been constructed to test shape memory alloys. With this machine it is possible to measure the internal friction anywhere in the stress—strain plot. The minimum strain amplitude for the measurements is near 10 −4 and the maximum frequency is 0.6 Hx. In this paper we present some preliminary results obtained on single crystals of CuZnAl shape memory alloys. The internal friction vs. temperature has been measured at various cooling—heating rates (from 0 to 1 K min −1). We have also measured the internal friction vs. deformation during a superelastic test (at T above A f ). This last experiment shows that the internal friction depends on the number of interfaces between the martensitic and austenitic phases.