Irradiation softening in a uranium containing NbTiZrU high entropy alloy induced by Xe ion implantation

In this work, a novel uranium-containing single-phase bcc NbZr0.6Ti0.4Ux (x = 0.4, 1, 2) high entropy alloy (HEA, named as U20, U50 and U100) film was designed and prepared. To evaluate their microstructural evolutionary behavior subsequent to implantation, the typical U50 sample was implanted with 5 MeV Xe+ ions at both room temperature (RT) and 350 degrees C with fluence ranging from 2.1 x 10(15) ions/cm(2) to 1.2 x 10(16) ions/cm(2). The same implantation tests were performed on pure Nb as a reference. TEM results showed that the NbZr0.6Ti0.4Ux film exhibits a vertically columnar crystal microstructure. When the implantation fluence is increased to 1.2 x 10(16) ions/cm(2) at RT, significant radiation-induced grain coarsening was observed, and the irradiation defects were largely absorbed during grain growth. Consequently, the average hardness is decreased with increasing the irradiation dose at RT. When the implantation is performed under 350 degrees C, the irradiation-induced softening behavior in the U50 sample becomes more pronounced, since more Xe accumulates along boundaries and the matrix is purified, and the irradiation hardening due to the Xe concentration was largely eliminated. In summary, NbZr0.6Ti0.4Ux shows superior resistance to irradiation, which provides a reference point for the further development and application of uranium-containing HEA in the nuclear field.