Memory metal sets flex record

An alloy that can bend and return to its original shape at least 10 million times could prove useful in applications including medical devices and refrigeration.

Bending a 'shape-memory alloy' changes its crystal structure from one phase to another, whereas applying heat reverses that transition. But structural damage causes these materials to lose their shape memory within a few thousand cycles. A team led by Eckhard Quandt at the University of Kiel, Germany, and Manfred Wuttig at the University of Maryland, College Park, has now created a titanium–nickel–copper alloy (Ti₅₄Ni₃₄Cu₁₂) that averts this memory loss. Layers of Ti₂Cu in the material act as templates that guide the complete transition between the two crystal phases.

This template approach could offer a way of creating better shape-memory alloys.

Science 348, 1004–1007 (2015)