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New material gives copper superalloy-like strength

Researchers from the U.S. Army Research Laboratory (ARL) and Lehigh University in Pennsylvania have developed a groundbreaking nanostructured copper alloy that could redefine high-temperature materials for aerospace, defense, and industrial applications.

This colorized scanning transmission electron microscope (STEM) image shows a Cu₃Li precipitate in the Cu-Ta-Li alloy. Orange features are primarily Cu atoms in the alloy matrix, while blue and yellow features correspond to the Cu₃Li precipitate. The yellow represents Ta atoms in the atomic bilayer complexion. Blue features represent Li atoms in the Cu₃Li precipitate core. [Credit: Lehigh University]

 

 

 

 

Their findings, published in the journal Science, introduce a Cu-Ta-Li (Copper-Tantalum-Lithium) alloy with exceptional thermal stability and mechanical strength, making it one of the most resilient copper-based materials ever created.

"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," said Martin Harmer, the Alcoa Foundation Professor Emeritus of Materials Science and Engineering at Lehigh University and a co-author of the study. "It provides industry and the military with the foundation to create new materials for hypersonics and high-performance turbine engines."

The ARL and Lehigh researchers collaborated with scientists from Arizona State University and Louisiana State University to develop the alloy, which can withstand extreme heat without significant degradation.

Combining copper with a complexion-stabilized nanostructure
The breakthrough comes from the formation of Cu₃Li precipitates, stabilized by a Ta-rich atomic bilayer complexion, a concept pioneered by the Lehigh researchers. Unlike typical grain boundaries that migrate over time at high temperatures, this complexion acts as a structural stabilizer, maintaining the nanocrystalline structure, preventing grain growth, and dramatically improving high-temperature performance.

The alloy holds its shape under extreme, long-term thermal exposure and mechanical stress, resisting deformation even near its melting point, noted Patrick Cantwell, a research scientist at Lehigh University and co-author of the study.

By merging the high-temperature resilience of nickel-based superalloys with copper -- which is known for exceptional conductivity -- the material paves the way for next-generation applications, including heat exchangers, advanced propulsion systems, and thermal management solutions for cutting-edge missile and hypersonic technologies.

A new class of high-performance materials
This new Cu-Ta-Li alloy offers a balance of properties not found in existing materials:

• Nickel-based superalloys (used in jet engines) are extremely strong but lack the high thermal conductivity of copper alloys.
• Tungsten-based alloys are highly heat resistant but dense and difficult to manufacture.
• This Cu-Ta-Li alloy combines copper's exceptional heat and electrical conductivity while remaining strong and stable at extreme temperatures.
• While not a direct replacement for traditional superalloys in ultra-high-temperature applications, this material has the potential to complement them in next-generation engineering solutions.

The team synthesized the alloy using powder metallurgy and high-energy cryogenic milling, ensuring a fine-scale nanostructure. They then subjected it to:

• 10,000 hours (over a year) of annealing at 800 C, testing its long-term stability.
• Advanced microscopy techniques, revealing the Cu₃Li precipitate structure.
• Creep resistance experiments, confirming its durability under extreme conditions.
• Computational modeling using density functional theory (DFT), which validated the stabilizing role of the Ta bilayer complexion.

The U.S. Army Research Laboratory was awarded a U.S. patent (US 11,975,385 B2) for the alloy, highlighting its strategic significance, particularly in defense applications such as military heat exchangers, propulsion systems, and hypersonic vehicles.

The scientists say further research will include direct measurements of the alloy's thermal conductivity compared to nickel-based alternatives, work to ready it for potential applications, and the development of other high-temperature alloys following a similar design strategy.

See the paper "A high-temperature nanostructured Cu-Ta-Li alloy with complexion-stabilized precipitates" in Science.

Source: Lehigh University

Published April 2025

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