China’s heat-resistant aluminum alloys are six times stronger than the previous ones

A team of Chinese scientists has developed a technique to make aluminum alloys significantly more heat resistant – overcoming a major obstacle with limited applications for the lightweight metal that is a critical component in areas such as aerospace and transportation.

Aluminum alloys are known for their low density, high specific strength and corrosion resistance. But until now their heat resistance has been relatively limited, with traditional aluminum alloys typically operating at a temperature of around 350 degrees Celsius (662 Fahrenheit). At temperatures above 400 degrees Celsius, the mechanical properties of these materials deteriorate rapidly, limiting their use in aerospace.

By adding nanoparticles in common aluminum alloys, scientists from the School of Materials Science and Engineering at Tianjin University (TJU) created a strengthened aluminum alloy which continued to perform well even at much higher temperatures.

“This new aluminum alloy has more than six times the strength of traditional aluminum alloys at 500 degrees Celsius, significantly exceeding the best levels reported internationally for aluminum-based materials,” TJU said in an official release earlier this month.

“This production process is simple, cost-effective and easy to scale up for industrial production, making it highly valuable for industrial applications,” lead researcher He Chunnian said in the release.

“The team is working with leading industry leaders and research institutions to advance the development of heat-resistant aluminum alloys for aerospace engines and critical aerospace components, and expects the material to see industrial use soon.”

The research was published on April 26 in the peer-reviewed journal Nature Materials.

The performance improvement of the aluminum alloy was achieved through the incorporation of highly stable nanometer-sized oxide particles. In addition to their low cost, the particles, which have a melting point above 1000 degrees Celsius, offer exceptional strength, thermal conductivity, heat resistance, oxidation resistance and corrosion resistance.

The process of incorporating ceramic particles into alloys to create oxide dispersion strengthened (ODS) alloys has shown promise. By 2022, NASA unveiled a similar method for producing the nickel-based NASA alloy GRX-810, which can withstand 1,093 degrees Celsius.

According to NASA’s website, the method has significantly improved the strength and durability of components and parts used in aviation and space exploration, resulting in better and more durable performance.

Although ODS alloys have been developed for reducible metals such as iron, molybdenum, nickel and tungsten through chemical processing methods, there are no commercially available ODS alloys for irreducible metals such as aluminum. magnesiumtitanium and zirconium, due to their high chemical reactivity with oxygen.

Unlike reducible metals, irreducible metals cannot be easily extracted from their oxide.

The Chinese research team achieved a uniform dispersion of ultrafine magnesium oxide nanoparticles in aluminum. Image: Handout

To tackle the problem, he and his team prepared 5nm magnesium oxide particles and then used powder metallurgy – a metal parts manufacturing process that compresses and sinters metal powders – to distribute the particles within the aluminum matrix, achieving an 8 percent volume fraction . .

“Our strategy resulted in ODS aluminum alloys with highly dispersive 5nm [magnesium oxide] nanoparticles through powder metallurgy,” the researchers said.

“The material shows really excellent properties,” said Alexis Deschamps, a renowned international expert in metallic materials from the Université Grenoble Alpes in France, in a Nature Materials news brief.

“This development opens up new possibilities for the application of aluminum alloys in high-temperature environments, where they could compete with some titanium alloys at a lower weight.”

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