Shape memory properties of Cu-based thin tapes obtained by rapid solidification methods

Two different rapid solidification techniques were utilized to produce thin tapes of Cu–13Al–xNi–1Ti (wt.%, with x = 5, 5.5, 6) shape memory alloys directly from the melt. Both melt-spinning and twin-roll casting (quenching between the gap of two rollers) have resulted successful methods to obtain ribbons (8 mm width, 55 μm thickness) and strips (29–30 mm width, 450 μm thickness) with grain sizes below 2 μm, after optimization of the processing parameters. Although as a consequence of the rapid solidification the martensitic transformation temperatures are depressed, after annealing at 700 °C the high transition temperatures of the alloys in the bulk form are re-established. Measuring of length change under uniaxial tensile load shows elongations up to 1.8% (at 90 MPa) on cooling through the martensitic transformation.