Thermoelectric triggering of phase transformations in Ni-Ti shape memory alloy

Shape memory alloys (SMA) which undergo solid-state transformations on heating and cooling can be potentially used as actuators, producing large actuation forces in compact smart systems. The frequency of actuation is, however, limited by a rate of heat transfer. In the present work, the thermoelectric Peltier effect is employed for heating and cooling of SMA. As a first step in design of the new actuator, Ni-Ti SMA and Bi-Te thermoelectric elements are assembled in the experimental units and the processes of the heat exchange inside them are studied. Compared with a conventional method of triggering of the transformations in SMA, cooling by the Peltier effect is found to be significantly faster. The obtained results are discussed in the terms of the energy balance and the optimal conditions for thermoelectric triggering of the transformations are found. Finally, some recommendations for design of the real actuator are suggested. (C) 1998 Elsevier Science S.A. All rights reserved.