Penn State researchers have uncovered a unique trend in which atoms will arrange themselves to find their preferred neighbor within multi-principal element alloys (MPEA). This arrangement behavior could provide a method for engineers to “tune” these unique materials.
MPEAs are a unique design approach differing from traditional alloys in that they consist of many principal elements all at nearly equal atomic ratios. This design provides unique properties applicable to a number of industries.
"Previously, alloys like steel were designed with one or two principal elements and trace elements to enhance performance," said Yang Yang, Penn State assistant professor of engineering science and mechanics and of nuclear engineering. "MPEAs use a different method, where all components are principal elements."
One major gap in our understanding of MPEAs has been the formation of short-range order (SRO) which is the non-random arrangement of atoms over short distances. In the research, published in Nature Communications, the researchers discovered that SRO is actually an inherent characteristic of MPEAs. SRO forms during the solidification process, and is created by atoms clustering in a specific order. This clustering could affect the material properties of MPEAs.
"Such materials are targeted for structural applications where mechanical performance is crucial, like in nuclear reactors or aerospace components," added Yang.
The findings of the study present an exciting opportunity for engineers to manipulate these SROs and fine-tune the MPEAs for specific applications. "Controlling the degree of SRO in MPEAs can possibly be achieved by mechanical deformation or radiation damage," added Penghui Cao, assistant professor in mechanical and aerospace engineering and materials science and engineering at the University of California. "This provides a new dimension to engineer the material's properties via tuning SRO-controlled mechanisms."
"Understanding how atoms find their neighbors, even at rapid cooling rates, helps us control the structure and enhance the performance of these innovative materials," Yang said. "This is still at the fundamental science stage, and I look forward to seeing how this develops."