Effect of mechanical vibration, heat treatment and ternary addition on the hysteresis in shape memory alloys
The martensitic phase transition which produces shape memory is connected with a hysteresis. Some of the applications of shape memory alloys require small hysteresis loops, other require large ones. It is therefore important to be able to control the size of the hysteresis. For that purpose three different methods were introduced in the present paper. Mechanical vibration narrowed the hysteresis loops in both NiTi and CuZnAl alloys by up to 17%, while the width of the hysteresis loops in an NiTi alloy was decreased 3 to 4 times by addition of a third element, copper. With the help of a special heat treatment a nearly hysteresis-free phase transition occurred in a Ti-51 at % Ni alloy. The size of the hysteresis is determined by the interfacial energies of the phase boundaries and these will be big, if the E-modulus and the lattic distortion are big.
KeywordsPolymer Copper Phase Transition Heat Treatment Hysteresis Loop
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- 1.G. Bensmann, F. Baumgart und J. Hartwig, Tech. Mitt. Krupp, Forsch. Ber. 37 (1979).Google Scholar
- 2.D. Stöckel, Metall 41 (1987) 494.Google Scholar
- 3.R. Banks, in Proceedings,“Shape Memory Effects in Alloys”, edited by J. Perkins (Plenum, 1975) p. 537.Google Scholar
- 4.D. M. Goldstein and L. J. McNamara (eds.) Proceedings of the Nitinol Heat Engine Conference, September 1978, Silver Spring, Maryland.Google Scholar
- 5.C. M. Wayman, in Proceedings of International Symposium on Shape Memory Alloys, edited by Y. Chu, T. Y. Hsu and T. Ko, Guilin, China, 1986, p. 59.Google Scholar
- 6.T. Honma, ibid. p. 83.Google Scholar
- 7.R. Kainima, M. Matzumoto and T. Honma, in Proceedings of International Conference of Martens, Trans. ICOMAT-86 (Japan Institute of Metals, Nara, Japan, 1986) p. 717.Google Scholar