How can we engineer materials that are both stronger and lighter? What about developing new materials capable of withstanding extreme conditions, such as those experienced in jet engines and spacecraft?
Fadi Abdeljawad, an associate professor of materials science and engineering at Lehigh University‘s P.C. Rossin College of Engineering and Applied Science, is delving into the minuscule realms where atoms in crystals converge, known as boundaries. Collaborating with experts at the U.S. Department of Energy’s Center for Integrated Nanotechnologies (CINT), Abdeljawad is unraveling the profound impact of these tiny boundaries on the properties of nanomaterials.
This research has the potential to reshape how we engineer materials for extreme conditions, paving the way for remarkable advancements in aerospace and other industries.
“Atoms come together to form nanocrystals, which are essentially structures about 1/10,000th the width of a human hair,” explains Abdeljawad. “Think of these crystals coming together like pieces of a puzzle or as tiles on a kitchen floor. Billions of these nanocrystals stack on top of each other to form most engineering materials.”
The researchers have discovered that the meeting points of crystals have a significant impact on how a material behaves.
The study delves into the crucial role of triple junctions in maintaining the stability of nanomaterials under high temperatures. This research sheds light on the fascinating world of nanomaterials and their potential applications.
Nanocrystalline materials possess an incredibly fine structure comprised of numerous minuscule crystals. This minute crystal size enhances the material’s strength. However, maintaining the stability of these tiny crystals over time presents a significant challenge, as they have a tendency to grow, potentially weakening the material.
In a groundbreaking study, researchers uncovered the secret to preserving the stability of these materials at high temperatures: the triple junctions, where three of these nanocrystals converge. Picture the meeting point of three puzzle pieces.
The pivotal finding reveals that by introducing specific atoms to create an alloy, these atoms preferentially occupy sites at these triple junctions. This “chemical segregation” or clustering of atoms at these junctions acts as a barrier to grain growth, effectively preserving the material’s strength over time.
Remarkably, the study showcased that strategically placing gold atoms at triple junctions within a platinum nanomaterial enabled the material to maintain stability even under high-temperature conditions.
“By understanding this process,” says Abdeljawad, “scientists can design better nanocrystalline alloys. They can choose specific elements that will go to the triple junctions and stabilize the material. This is particularly important for applications where strength and durability at elevated temperatures are key, such as in the aerospace and energy industries.”
Abdeljawad, an accomplished computational materials scientist at Lehigh University, conducted extensive and sophisticated computational studies that astutely anticipated these groundbreaking results. To validate the accuracy of the models, the adept computational team established a collaborative partnership with the Center for Integrated Nanotechnologies (CINT).
Renowned for its state-of-the-art tools and unparalleled expertise in nanoscale research, CINT empowers cutting-edge explorations in materials science, nanofabrication, and nanophotonics, propelling scientific and technological advancements to new heights.
“This is an outstanding example of collaborative science,” says Dr. Brad Boyce, a senior scientist at CINT and a co-author of this study. “Our ideas for how to engineer novel materials by tailoring features at the nanoscale are maturing as a result of the ability to simulate the complex arrangement of atoms that make up these materials.”
Journal reference:
- Annie K. Barnett, Omar Hussein, Maher Alghalayini, Alejandro Hinojos, James E. Nathaniel II, Douglas L. Medlin, Khalid Hattar, Brad L. Boyce, Fadi Abdeljawad. Triple Junction Segregation Dominates the Stability of Nanocrystalline Alloys. Nano Letters, 2024; DOI: 10.1021/acs.nanolett.4c02395
