Scientists at the City University of Hong Kong have discovered a first-of-its-kind alloy that becomes stiffer rather than softer when heated to a high temperature.

Until now, it was believed that all metals soften when their temperature rises due to thermal expansion.

Indeed, the high-entropy elinvar becomes stiffer and more springy as the temperature approaches 1,000 K (727°C, 1,341°F). None of the known metals behaves in this way.

“When this alloy is heated to 1000 K, that is, to 726.85 °C, or even higher, it becomes the same or even slightly stiffer than at room temperature, and it expands without any noticeable phase transitions. This is contrary to all textbook information, as metals tend to soften when they expand when heated,” Yang Yong, co-author of the study.

In addition to the elinvar effect, this alloy also exhibits an elastic limit of about 2 percent at room temperature, meaning that although you need to put a lot of energy to deform it, it will take about twice as long to deform than a regular crystalline alloy before any permanent deformation.

The graph shows that the modulus of elasticity of the new alloy increases with increasing temperature.

“Because elasticity does not dissipate energy and therefore does not generate heat that can cause devices to malfunction, this superelastic alloy will be useful in high-precision devices such as watches and chronometers.

We know that temperatures on the surface of the moon range from -122°C to -232°C. But this alloy will remain strong and undamaged under extreme conditions and is therefore very well suited for future mechanical timepieces operating over a wide temperature range during spaceflight,” says Yang Yong.

In the video below, you can see the extraordinary elastic capacity of the high-entropy alloy in comparison to other materials.

According to scientists, such amazing properties of this alloy can be useful in the space industry, which needs materials that can withstand significant temperature changes.

bbabo.Net