High-strength gradient Ti-Ni-Cu-Pd ribbon with large recoverable strain and high cyclic stability under load

Abstract

Bulk Ti-Ni-Cu-Pd alloys show decent thermal- and load-cycling stability, yet low strength and limited recoverable strain. Here, we design a gradient Ti-Ni-Cu-Pd ribbon via nanoscale dual-phase (nanocrystalline-amorphous) engineering. The ribbon achieves 1-2x higher strength than bulk austenite while delivering similar to 4% fully recoverable strain (bulk well below 3%). Under high load, the strain amplitude declines only 0.5-0.7% after 10 loading cycles, demonstrating exceptional cyclic stability. These properties arise from phase synergy across the gradient architecture, enabling compact, high-force, repeatable actuators. [GRAPHICS]