INTERNAL FRICTION STUDY OF STRESS-INDUCED MARTENSITIC TRANSFORMATION IN Cu-Zn-Al SHAPE MEMORY ALLOYS

The method of internal friction has been used for studying stress-induced martensitic transformation in Cu-Zn-Al polycrystals. The observed internal friction spectrum for a given pseudoelastic cycle is a unique, non-linear function of the transformation rate, and is independent of the actual amount of transformed volume. The internal friction values decrease with increasing stress cycling temperature, indicating that only at sufficiently high temperatures above Ms is a perfectly oriented martensitic structure obtained