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Thermal memory degradation in a Cu-Zn-Al shape memory alloy during thermal cycling with free air cooling

Domenii publicaţii > Stiinte ingineresti + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: L. G. Bujoreanu, N. M. Lohan, B. Pricop, N. Cimpoeşu

Editorial: Springer, Journal of Materials Engineering and Performance, 20(3), p.468-475, 2011.

Rezumat:

A fragment of a Cu-15Zn-6Al (mass%) shape memory alloy (SMA), in hot rolled-water quenched condition,was subjected to thermal cycling performed by means of a differential scanning calorimetry (DSC) device.Each cycle comprised controlled heating, isothermal maintaining, and free air-cooling, repeated three times,up to maximum temperatures increased by every 10 K, between 450 and 490 K, aiming to reproduce actual functioning conditions of a SM electrical actuator with controlled cooling. Both the endothermic peaks, associated with thermally induced reversion of martensite to austenite, and their derivatives were analyzed in terms of critical transformation temperatures and specific enthalpy absorptions and in terms of transformation rates, respectively, with the aim of revealing their variational tendencies with increasing heating temperature to the maximum. The progressive decay of reverse martensitic transformation was associated with the reciprocal blocking of differentially oriented populations of stabilized lath-martensite needles,
observed by scanning electron microscopy.

Cuvinte cheie: differential scanning calorimetry, metallography, reverse martensitic transformation, stabilization, thermalmal cycling

URL: http://www.springerlink.com/content/1059-9495/20/3/