MIT researchers have developed a way to watch how materials break down inside nuclear reactors while it is occurring. Corrosion means the slow destruction of metal by chemical reactions, and cracking refers to splits forming in the material. They use very strong X-rays to imitate neutrons - tiny particles in reactors that damage materials through irradiation, or exposure to radiation. This setup lets scientists see failures in three dimensions without stopping the process.
In experiments, they tested nickel, a metal often used in reactor alloys (mixtures of metals for strength). To prepare samples, they applied solid state dewetting, heating a thin nickel layer on a base until it forms crystals. But the nickel reacted with the silicon base, forming unwanted compounds. To fix this, the researchers added a buffer layer of silicon dioxide, a common insulating material like glass, between them.
Unexpected benefits from the method
This buffer stopped reactions and helped stabilize the sample. When crystals formed, they had strain (distortions where atoms shift positions). Phase retrieval algorithms, computer methods to rebuild 3D shapes from data, usually fail with high strain. But keeping the X-ray beam on longer relaxed the strain, allowing accurate 3D imaging of failures like corrosion in real time, similar to reactor conditions.
The technique could extend reactor life by improving materials to resist irradiation stress better. An unexpected surprise was using X-rays to control strain precisely, which might help in microelectronics by adjusting crystal structures for better performance.
In the future, researchers plan to test complex materials like steel for reactors and aerospace. They also want to vary the buffer layer thickness to fine-tune strain control. This work provides insights into how tiny materials react to radiation, important for energy, electronics, and quantum tech, and shows the base surface's role in strain changes.
The researchers have described the methods and results of this study in a paper published in Scripta Materialia.