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Updated: Jan 26, 2026

Processing of Bulk Nanocrystalline Metals at the US Army Research Laboratory
Published on: March 7, 2018
Thermal stability and irradiation response of nanocrystalline CoCrCuFeNi high-entropy alloy
Yanwen Zhang1,2, Matheus A Tunes3, Miguel L Crespillo2
1Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America.
Abstract:
Grain growth and phase stability of a nanocrystalline face-centered cubic (fcc) Ni0.2Fe0.2Co0.2Cr0.2Cu0.2 high-entropy alloy (HEA), either thermally- or irradiation-induced, are investigated through in situ and post-irradiation transmission electron microscopy (TEM) characterization. Synchrotron and lab x-ray diffraction measurements are carried out to determine the microstructural evolution and phase stability with improved statistics. Under in situ TEM observation, the fcc structure is stable at 300 °C with a small amount of grain growth from 15.8 to ∼20 nm being observed after 1800 s. At 500 °C, however, some abnormal growth activities are observed after 1400 s, and secondary phases are formed. Under 3 MeV Ni room temperature ion irradiation up to an extreme dose of nearly 600 displacements per atom, the fcc phase is stable and the average grain size increases from 15.6 to 25.2 nm. Grain growth mechanisms driven by grain rotation, grain boundary curvature, and disorder are discussed.
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