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Structural Effects of Training Cycles in Shape Memory Actuators for Temperature Control

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

Autori: G. Vitel, Marius-Gabriel SURU, A. L. Paraschiv, N. M. Lohan, B. Pricop, M. Baciu & L. G. Bujoreanu

Editorial: Materials And Manufacturing Processes, Vol. 28, No. 1, p.79–84, 2013.


Lamellar thermal actuators, for temperature control in hydraulic systems, were manufactured from a Cu-Zn-Al shape memory alloy and
trained in bending, between 100 and 500 cycles. The cycles were performed automatically and comprised electrical heating and ventilated
air cooling during which a load, fastened at actuator’s free end, was lifted by shape memory effect and lowered by martensite-formation
softening, respectively. The structural effects of training, evaluated by differential scanning calorimetry (DSC), optical and atomic force
microscopy, consisted in a shifting tendency to higher values of critical transformation temperatures of martensite reversion to parent phase
and in a noticeable decrease of surface micro-relief accompanying the occurrence of martensite plates oriented according to a single direction.
The critical temperature of the start and finish of martensite reversion to parent phase (As and Af, respectively) were determined both
by means of the deflectograms (curves of specimens free end displacement vs. temperature) and of the DSC charts. The structural effects
of training cycles were evaluated, as well, byAFMmeasurements of martensite plates. The average measured widths and heights of martensite
plate profiles decreased almost seven and almost four times, respectively, after 500 training cycles.

Cuvinte cheie: DSC; Martensite; Relief; SMA; Training