The research group of Toshihiro Omori, Associate Professor of the Graduate School of Engineering, Tohoku University, and Ji Xia graduate students has succeeded in developing an iron-based superelastic alloy with almost no temperature dependence of strength for the first time in the world.The strength (stress) hardly changes from extremely low temperature to 200 ° C, and it can be used almost without being affected by temperature changes.
The superelastic alloy returns to its original shape even if it is subjected to a large deformation, except for the force.Currently, nickel-titanium alloys are mainly used in medical devices and the like.The disadvantage is that as the temperature rises, the deformation strength increases and the mechanical properties are not stable, so the temperature range in which superelasticity develops is narrow.With nickel-titanium alloys, the stress increases by about 1 megapascals (MPa) when the temperature rises by 6 ° C, and the temperature range in which superelasticity can be practically used even if the material composition is changed is approximately -20 ° C to 100 ° C. Limited.
The newly discovered iron-based superelastic alloy is an alloy containing iron as the main component and manganese, aluminum, nickel, and chromium.It has the characteristic that the strength (stress) hardly changes even if the temperature changes.The temperature range in which stress fluctuations are within 50 megapascals is limited to the range of about 8 ° C near room temperature for nickel-titanium practical alloys, but for this iron-based superelastic alloy, it is about 400 from extremely low temperatures to a hundred and several tens of degrees Celsius. Over ° C.This covers not only the temperature range on Earth, but also the temperature range on the Moon and Mars.Further, by adjusting the composition, it is possible to obtain a property that the strength decreases as the temperature increases, which tends to be different from that of a normal superelastic alloy.
The extremely low temperature dependence of strength has great advantages for the use of superelastic alloys in environments exposed to many temperature changes.It is expected to be used in a wide range of applications such as use in extraterrestrial environments where temperature changes are drastic, and development of building and civil engineering seismic control structural systems.
Paper information:[Science] Iron-based superelastic alloys with near-constant critical stress temperature dependence
