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

Abstract

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 m thickness) and strips (29–30 mm width, 450 m thickness) with grain sizes below 2 m, 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.