Scientists in Japan have designed an elastic iron-based shape metal alloy for use in applications as diverse as heart and brain surgery and buildings in earthquake-prone areas.
The researchers, from Tohoku University, said the ferrous polycrystalline shape memory alloy was as strong as high-strength industry alloys, but it is also superelastic, which means it can return to its original form when strain is removed and the material is heated, an important property of all shape memory alloys. The iron alloy even returns to its former shape when under almost twice the strain levels endured by current shape memory alloys. The alloy also exhibits changes in ductility and a large reversible change in magnetization during shape transitions.
The alloyâ€™s stress level is around double that of the shape memory alloy nickel-titanium, which means it can be formed into extremely thin wire. At present the nickel-titanium alloy is the only superelastic alloy available for practical use. Superelastic properties make a shape memory alloy ideal for delivering stents to parts of the body such as the heart since they can expand to a wider diameter when warmed by the body. Stents are tubes that are surgically implanted into blood vessels to prevent them collapsing.