AUSTENITIC MARTENSITIC INTERFACE DAMPING MEASURED IN SHAPE-MEMORY ALLOYS BY A CYCLIC TENSILE MACHINE

A tensile machine has been constructed to test shape memory alloys. Wi th this machine it is possible to measure the internal friction anywhe re in the stress-strain plot. The minimum strain amplitude for the mea surements 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 dur ing 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.