Synergistic effect of nanotwins and compositional entropy on the radiation resistance of CoCrFeNi thin films, Acta Materialia 299,121420(2025)
Wei-Cheng Chang, Maulik K. Patel, Wan-Zhen Hsieh, Ching-Yu Chiang, Fan-Yi Ouyang*
2025/12/04
High entropy alloy (HEA) thin film and high density of nanotwinned (NT) structure demonstrated superior radiation resistance compared to traditional metallic alloys and nanocrystalline thin film; however, their synergistic effect remains to be explored. In this study, CoCrFeNi HEA thin films consisting of NTs with an average twin spacing of 2 nm were synthesized by a pulsed direct current sputtering technique, and their corresponding radiation resistance investigated at room temperature with 275 keV helium radiation damage in the fluence of 5 × 1016, 1.5 × 1017 and 4.5 × 1017 He/cm2, respectively. With the analysis of transmission electron microscope and synchrotron x-ray diffraction, the NT-HEA thin films showed stable grain size (21.2–23.1 nm) and twin spacing (1.6–2 nm) after irradiation. The distribution and the size of helium bubbles (less than 0.5 nm) demonstrated great radiation resistance of NT-HEA films. The interaction of defects with grain boundaries (GBs) and nanotwinned boundaries (NTBs) was observed in the results. Furthermore, phase transformation from face-centered cubic phase (FCC) to hexagonal closed packed phase (HCP) was found due to the radiation-induced local strain. The tremendous local strain also induced grain rotation in the NT-CoCrFeNi films after ion irradiation. The present work provides a new insight into the improvement of radiation resistance through the synergistic effects of sluggish diffusion in HEA and nanotwinned structures.
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