Electric Transport Properties of NiTi Thin Wires Under Applied Stress
INFM, Unità di Milano Università, via Celoria 16, 20133 Milano, Italy
2 Università di Milano, Dipartimento di Fisica, via Celoria 16, 20133 Milano, Italy
In recent years, the electric transport properties of NiTi and NiTiCu alloys under applied stress have been investigated either in the martensitic phase or in the austenitic one. Moreover, with the aim to use the electrical resistance (ER) as a state control variable of a shape memory actuator, the ER has been investigated either in the recovery process under stress or in the two way memory effect (TWME). In relation to the recovery process and the TWME, the ER vs ε shows, in the transformation region (i.e. the "operating" temperature range), a linear trend, which appears appealing for the control of the shape memory actuator. While the interest in microactuators is steadily growing, results on ER vs. ε in thin wires are still lacking. In the present paper, the ER vs. ε has been investigated in thin NiTi wires (ф=25Oμm), where the strong drawing is expected to induce textures and the surface-to-volume ratio is higher than in the previous investigations. The results here obtained are compared and contrasted in the light of the previous results detected on NiTi alloys.
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