Study of Two-Way Shape Memory Behavior of Amorphous-Crystalline TiNiCu Melt-Spun Ribbons

Abstract

Recently we reported on the development of a composite material exhibiting reversible shape memory effect. A Ti–25Ni–25Cu (at.%) alloy was obtained by the melt spinning technique as amorphous–crystalline ribbons with a thickness of approximately 40 μm. The thickness of the amorphous and crystalline layers (d а and d c , respectively) was varied by electrochemical polishing. It has been ascertained that with varying the relationship d c /d а the martensite transformation and shape-recovery temperatures do not actually change, while the minimum radius of the ribbon bending decreases from 8.0 mm to 2.4 mm with increasing the relationship d c /d а from 0.33 to 1.40. The maximum reversible strain comprises 0.4% at d c /d а = 0.82. On the basis of experimental data obtained the phenomenological description, providing an explanation for nature of the phenomena taking place in the rapidly quenched amorphous-crystalline ribbon composite, has been proposed.