UW Ph.D. Student Makes Breakthrough with Potential to Revolutionize Materials Development

The University of Wyoming's Lauren Kim has solved a persistent problem in the cutting-edge field of high-entropy alloys, a class of materials with great potential in modern engineering, electronics and energy applications -- such as jet engines, nuclear reactors, chemical processing systems, batteries and supercapacitors -- along with cryogenics systems.

Kim, from Fairport, N.Y., was a Ph.D. student in UW's Department of Physics and Astronomy who graduated in December, working under the direction of Professor TeYu Chien. Their article, "Revealing the Existence of the Surface Local Chemical Ordering in High Entropy Alloys," appeared this month in the academic journal Nature Communications.

In it, Kim and co-authors describe their research into a novel method of identifying the chemical arrangement of the surfaces of this specialized class of alloys.

Traditional alloys generally feature only two elements in combination, with one in greater abundance. High-entropy alloys combine five or more elements in nearly equal proportions. This greater number of elements allows for the development of materials with greater strength with increased entropy, ideal for applications requiring high strength, corrosion resistance and thermal stability.

The elements in high-entropy alloys, however, exist in a solid solution crystalline structure and, while the distribution of the atoms of each element is not fully random, neither is it regular. So, the precise location of each element relative to another in the alloy, or local chemical ordering, has not been unambiguously determined with available detection technologies.

While it is reasonable to assume that the existence of local chemical ordering may affect the material properties -- such as mechanical strength, catalytic activities, corrosion resistance and thermal stability -- establishing these relationships with the existence of local chemical ordering on an alloy has been nearly impossible.

This is what makes Kim and her team's recent breakthrough so exciting. Their methodology has, for the first time, made it possible to characterize surface local chemical ordering of high-entropy alloys.

This work, made possible through a National Science Foundation grant, is a result of collaboration between Kim and Chien at UW, together with Ganesh Balasubramanian and Prince Sharma, from the University of New Haven (Sharma will join UW's Department of Mechanical Engineering this fall); Peter Liaw, from the University of Tennessee-Knoxville; E-Wen Huang, from National Yang Ming Chiao Tung University in Taiwan; and Che-Wei Tsai and Jien-Wei Yeh, from National Tsing Hua University in Taiwan. Notably, Yeh was the first researcher to demonstrate the stability of high-entropy alloys more than 20 years ago.

In particular, this team worked with the alloy CoCrFeMnNi (cobalt, chromium, iron, manganese and nickel). The method involves using surface-sensitive scanning tunneling microscopy to reveal elements at the atomic scale. This gives a good view of quasi-long-range ordering, which is the atomic distribution ordering detectable at a slightly larger scale. Next, density functional theory calculations identify the finer resolution of local chemical ordering within those quasi-long-range supercells. Through these methods, the team directly observed and characterized surface local chemical ordering of high-entropy alloys.

"This finding implies that the surface physical/chemical properties of high-entropy alloys can be controlled together with controlling the local chemical ordering. And we demonstrated a new tool/methodology to study local chemical ordering in high-entropy alloys, which is unprecedented," Chien says.

Kim's methodology could lead to exciting advances in the ability to better control the properties of alloys to yield custom materials with superior strength, stability and resistance to corrosion.

The full article is available at https://www.nature.com/articles/s41467-026-71170-z.