New copper alloy achieves unprecedented high-temperature performance

A team of researchers from Arizona State University, the U.S. Army Research Laboratory (ARL), Lehigh University and Louisiana State University has developed a high-temperature copper alloy that it says offers exceptional thermal stability and mechanical strength. The novel bulk copper-tantalum-lithium (Cu-3Ta-0.5Li) nanocrystalline alloy exhibits notable resistance to coarsening and creep deformation, even at temperatures near its melting point.

The discovery opens new avenues to develop next-generation copper alloys for applications in the aerospace, energy and defense industries, according to a news release from Arizona State University. Potential uses could include heat exchangers, high-performance electrical components, weaponry and structural materials requiring durability in extreme conditions.

Currently, nickel-based (Ni-based) superalloys, known for exceptional strength, corrosion resistance and high-temperature stability, are the primary material used in applications where these properties are critical, such as aerospace components, gas turbine engines and chemical processing equipment.

“Our alloy design approach mimics the strengthening mechanisms found in Ni-based superalloys,” says Kiran Solanki, a professor at the Ira A. Fulton Schools of Engineering in the School for Engineering of Matter, Transport and Energy and a co-author of the study.

“When we look inside our body, we try to look for fingerprints of cell mutation for cancer,” Solanki says. “Similarly, structural materials have a unique fingerprint when they are subjected to any event like radiation or heat. They will leave behind a fingerprint, which causes them to fail or not to perform the way they should perform.”

The newly engineered alloy owes its superior properties to a nanoscale structure featuring precisely ordered copper lithium precipitates surrounded by a tantalum-rich atomic bilayer, the researchers say. The addition of precisely half a percent of lithium to the previously unmixable copper-tantalum system alters the precipitate morphology, changing the sphere-like precipitate in Cu-Ta system into a stable cuboidal structure that enhances thermal and mechanical performance, the researchers say.

“And in this case, having a copper lithium precipitate with a stable bilayer of Ta is when we can alter [the] high temperature fingerprint for failure,” Solanki explains. “By manipulating fingerprints, we have developed a copper alloy that maintains its strength and structural integrity even after prolonged exposure to high temperatures.”

“This is cutting-edge science, developing a new material that uniquely combines copper’s excellent conductivity with strength and durability on the scale of nickel-based superalloys,” says Martin Harmer, the Alcoa Foundation Professor Emeritus of Materials Science and Engineering at Lehigh University and a co-author of the study in a news release. “It provides industry and the military with the foundation to create new materials for hypersonics and high-performance turbine engines.”

The copper superalloy offers enhanced thermal stability, remaining stable at 800 C (1,472 F) for more than 10,000 hours, with minimal loss in yield strength. It also outperforms existing commercial copper alloys, achieving a yield strength of 1,120 megapascals at room temperature. Additionally, the alloy exhibits significantly lower creep deformation compared with conventional Cu-Ta alloys, making it ideal for high-stress, high-temperature environments.

According to the news release from Lehigh University, “While not a direct replacement for traditional superalloys in ultra-high temperature applications, it has the potential to complement them in next-generation engineering solutions.”

“This research not only advances our understanding of alloy design but also paves the way for materials that can withstand extreme environments,” says Kris Darling, an ARL co-author of the study. “The manipulation of fingerprints through nanostructuring in alloy could revolutionize the way we approach high-temperature material development.”

The study, titled “A High-Temperature Nanostructured Cu-Ta-Li Alloy with Complexion-Stabilized Precipitates,” has been published in the journal Science and was supported by the U.S. Army Research Laboratory, the National Science Foundation and Lehigh University’s Nano-Human Interfaces Initiative.