Lawrence Livermore National Laboratory has learned new information about zirconium, a material that may be critical in nuclear energy and military applications. The results provide new insights into the complex deformation mechanisms in materials, which could pave the way for tougher and more eco-friendly materials.
Unveiling the Atomic Disorder
Materials for extreme conditions (nuclear energy or military applications) must be able to withstand extremely high pressures, temperatures and corrosion. These materials are key for developing future technologies that will increase reliability, lower cost and improve sustainability, but to move forward in their development it is critical to understand how they behave atomically.
Harnessing the metal zirconium — widely used for nuclear fuel rod cladding because of its high strength and low neutron absorption — as a debut model, researchers at Lawrence Livermore National Laboratory looked well beyond its published New Model Simulation (NMS) results. The team reports that by compressing single-crystal samples of zirconium at high pressure, they found the material deformed in a very complicated manner—all but unprecedented in polycrystalline zirconium.
By using state-of-art experimental methods, including in-situ femtosecond X-ray diffraction images-his research team unambiguously proved that metal isolators can intrinsically possess atomic disorder-which is never before observed in any elemental metals. The discovery contradicts previous understanding of how metals deform at high temperatures and pressures, and could have important implications for the design and improvement of materials.
Many Ways to Transform
On top of the surprising detection of atomic disorder, more paths for zirconiums crystal structure transformation due to high-pressure have been established by the researchers. This is just another example of a unique observation, articulating another interesting complexity in its properties.
Compressing metals normally deforms them due to the movement of defects called dislocations on certain crystallographic planes and directions. The behavior of zirconium, on the other hand, was more complex because the crystal structure altered by multiple pathways.
The researchers also explored multi-million atom molecular dynamics simulations with a machine-learned potential to verify their experimental observations. These simulations provided deep insights into the full choreography of atomic motion and confirmed the sophisticated deformation mechanisms that had been measured in the experiments.
Finding these numerous paths to phase transition within a single material, all under extreme conditions, is an important step forward in our basic understanding of material behavior and could lead to the development of more durable and efficient materials for infinite applications.
Conclusion
We believe that the research conducted by this team may provide a new understanding on how metals deform under extreme conditions, revealing just how complicated and intricate this really is. The results represent an unexpected question of atomic disorder in zirconium and reveal a range of pathways for crystal structure transformation that defy established models, suggesting new avenues for developing next generation materials that could be more resilient, economical and sustainable. As he notes, these results extend well beyond the world of nuclear energy, or even defense; they demonstrate why we must continue to invest in science and material research to develop new technologies.
