Surface Morphology Evolution, Microstructural Response and Mechanical Property Variation of Au-ion Irradiated CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr High-Entropy Alloy Coatings

In this work, the CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr refractory high-entropy alloy (RHEA) coatings (1.67 similar to 2.77 mu m of thickness) were prepared by magnetron sputtering. Then, 6 MeV Au-ion irradiations with 2.5 x 10(15) to 1.0 x 10(16) ions/cm(2) fluences were performed on these coatings at 473 K, and the surface morphology, microstructure and mechanical property were investigated. The peak damage of the CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr coatings under 1.0 x 10(16) ions/cm(2) fluence are 48, 48, 44, 48 and 48 dpa, respectively. The peak Au concentration of the CrNbZrMoV, TiCrZrMoV, TiNbCrMoV, TiNbZrCrV and TiNbZrMoCr coatings under 1.0 x 10(16) ions/cm(2) fluence are 4.27 x 10(3), 4.12 x 10(3), 4.13 x 10(3), 4.16 x 10(3) and 4.37 x 10(3) appm, respectively. The surface morphology of the CrNbZrMoV, TiCrZrMoV, TiNbZrCrV and TiNbZrMoCr coatings were smoothed obviously. For BCC TiNbCrMoV coating, irradiation caused the growth of the nanocrystalline. For amorphous coatings, the crystallization occurred in the CrNbZrMoV, TiCrZrMoV and TiNbZrMoCr coatings after 2.5 x 10(15) fluence irradiation (>= 12 dpa), while the TiNbZrCrV coating remain mainly amorphous structure after all irradiation. It was found that irradiation induced continuous crystallization occurred not only at the surface but also in the peak damage zone of the coating, and then grew inside the irradiated region. Apparent irradiation hardening was observed in all the coatings except the TiNbZrCrV coating. The structural stability of these coatings under the current irradiation condition was discussed. Preliminary study shows that the great irradiation tolerance of amorphous TiNbZrCrV coating may be related to the lowest electronegativity difference (Delta chi = 0.121) and large atomic size difference (delta = 9.042 %) that stabilize the structure and inhibit atomic diffusion, respectively. These findings provide the guidance for the development of high irradiation tolerance materials for future nuclear energy applications with great structural stability.