Stress-assisted two-way memory effect electrically driven in 50at.%Ti-45 at. %Ni-5 at. %Cu alloy

Electrical resistance (R) and deformation (epsilon) are studied in Ti-45 at.%Ni-5 at.%Cu alloy, electrically driven through the transformation range under different constant stress levels in the range 10-500 MPa. Specimens with increasing preliminary cold-work levels (13, 19, 28 and 45%) were selected, in order to single out the condition sigma(crss) (critical resolved shear stress) > sigma(a) (applied stress). In the following, attention is focussed on specimens with 45% cold work, which were submitted to 1000 cycles under constant stress levels of 50, 75 and 100 MPa. A linear relationship between electrical resistance change and strain was obtained under all such conditions, with no accumulated residual strain, for an applied stress of 50 MPa. For the higher stress levels investigated, a small decreasing residual strain appears during the first 500 cycles, which then levels off for a greater number of cycles.