• Schell, Norbert
• Martins, R. M. S.
• Paula, A. S.
• Silva, Rui J. C.
• Canejo, J.
• Fernandes, Francisco Manuel Braz
• Cardoso, A. M. A.
• Mahesh, Karimbi Koosappa

Abstract

Anisotropy of the shape recovery associated with shape memory effect strongly depends on the present type of preferential orientation, as well as the ‘strength' of the texture. This paper reports the results obtained by the in-situ study of texture evolution during the annealing process in Tirich Ni-Ti Shape Memory Alloys (SMAs) with different thermal and mechanical histories. For this purpose, a Be-dome furnace installed into a 6-circle goniometer at the BM20 beamline (ROBL-CRG) at the ESRF (Grenoble) has been used. It is shown that there is a significant change in the preferential orientation of B2 phase, with the change in microstrain/coherence domain size, as a function of annealing temperature. This effect is also observed in the B19' phase after cooling. The α-fiber II (austenite texture - <110>||RD ({111}<110>-{110}<110>) was present in the as-received alloy, but only up to 400ºC. The evolution of {111}<110> austenite texture component is quite clear for annealing temperatures above 400ºC.

Topics

• impedance spectroscopy
• phase
• strength
• texture
• annealing