Chiara Bellamoli / KIT
Production of alloys by arc fusion in the KIT materials synthesis laboratory
New-generation heat-resistant material shows great potential for applications such as energy-efficient aircraft turbines.
A team of scientists from the Karlsruhe Institute of Technology (KIT), in Germany, created a league of chromium-molybdenum-silicon which withstands extreme heat, remaining ductile and resistant to oxidation, and which could replace nickel-based superalloys, which are limited to around 1100°C.
The new material could make turbines and engines significantly more efficient, marking an important step towards cleaner energy systems and powerful.
Os high temperature metals they are essential for powering aircraft engines, gas turbines, x-ray systems and other advanced technologies. Among the most resistant to heat are refractory metals such as tungstenmolybdenum and chromium, all with melting points around or above 2000 degrees Celsius (~3600 degrees Fahrenheit).
Despite their exceptional heat tolerance, these metals present major challenges: are fragile at normal temperatures and oxidize quickly when exposed to oxygen, leading to failure even at 600 or 700 degrees Celsius (~1100 to 1300 degrees Fahrenheit). Because of this, they can only be used in special vacuum environments, such as rotating X-ray anodes.
To overcome these limitations, engineers usually resort to nickel-based superalloys for components that have to withstand hot air or combustion gases. These materials are standard in gas turbines and other high temperature systems.
The results of the research were presented in a recently published in the journal Nature.
“Existing superalloys are made up of many different metallic elements, including some rarely available ones, in order to combine several properties. They are ductile at room temperature, stable at high temperatures and resistant to oxidation”, he explains Martin Heilmaier, researcher at the Institute of Applied Materials at KIT, in .
“However – and here is the problem – the operating temperatures, i.e. the temperatures at which they can be used safely, are in the range up to 1100 degrees Celsius maximum“, he adds.
“This is too low to exploit the full potential for greater efficiency in turbines or other high-temperature applications. The truth is that efficiency in combustion processes increases with temperature”, explains the researcher.
A technological leap
Recognizing this performance limit, Heilmaier’s team set out to find a new solutionand developed a new metallic alloy, which combines chromium, molybdenum and silicon.
This superalloy of refractory metals, in whose discovery Alexander Kauffmancurrently a professor at the Ruhr University in Bochum, played a fundamental role, presents never-before-seen properties.
“It is ductile at room temperature, its melting point is so high how much about 2000 °C. Furthermore, unlike the refractory alloys known to date, oxidizes only slowlyeven in the critical temperature range,” explains Kauffman.
“This opens up the possibility of manufacture suitable components for operating temperatures substantially above 1100 °C. Thus, the result of our study has the potential to allow a true technological leap“, afirma Kauffmann.
This is particularly notable since oxidation resistance and ductility are still cannot be sufficiently predicted to enable targeted materials design – despite the great progress made in computer-aided materials development.
“In a turbine, even a temperature increase of just 100 degrees Celsius can reduce fuel consumption by around five percent“, explica Heilmaier.
“That is particularly relevant to aviationas electrically powered planes are unlikely to be suitable for long-haul flights in the coming decades. Therefore, a significant reduction in fuel consumption will be a vital issue”, he adds.
“With our discovery, we have reached an important milestone. Research groups around the world can now build on this achievement”, concludes the researcher.
