One of the first things we learn in science class in school is that metals expand as temperature rises. Think of your metal garage door which is easy to open and close in winter, but is decidedly stiffer in summer.
One material that challenges this theory somewhat is Invar, a nickel-iron alloy that exhibits very low thermal expansion. The reason for that had been something of a mystery, until now.
The new, temperature-resistant alloy
Theoretical researchers from the University of Vienna in Austria teamed up with experimentalists from the University of Science and Technology Beijing in China to undertake complex computer simulations which have helped them understand Invar’s properties. From there, they have been able to develop what they have named pyrochlore magnet, a new alloy made up of multiple metals which is almost completely resistant to temperatures.
Invar 2.0, if you will.
For science boffins, its length, according to Sci Tech Daily, changes by “about one ten-thousandth of one percent per Kelvin over an exceptionally wide temperature range of more than 400 Kelvins”. For everyone else, that’s the smallest amount imaginable whatever the temperature change.
How to eliminate thermal expansion
According to Dr Segii Khmelevskyi from the Vienna Scientific Cluster (VSC) Research Centre, which is part of the university, the key was finding materials which cancel each other out, thus (almost) eliminating thermal expansion.
“The higher the temperature in a material, the more the atoms tend to move – and when the atoms move more, they need more space. The average distance between them increases. This effect is the basis of thermal expansion and cannot be prevented. But it is possible to produce materials in which it is almost exactly balanced out by another, compensating effect.”
What could pyrochlore magnet be used for?
The pyrochlore magnet is made up of four components that do just that: zirconium, niobium, iron, and cobalt. The material is likely to be of significant interest in fields in which extreme temperature changes are common or precise measuring techniques are required, such as aviation, aerospace or high-precision electronics.
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