Abstract
The FeCoNiCrTi0.2 high-entropy alloys fabricated by vacuum arc melting method, and the annealed pristine material, are face centered cubic structures with coherent γ’ precipitation. Samples were irradiated with 50 keV He+ ions to a fluence of 2 × 1016 ions/cm2 at 723 K, and an in situ annealing experiment was carried out to monitor the evolution of helium bubbles during heating to 823 and 923 K. The pristine structure of FeCoNiCrTi0.2 samples and the evolution of helium bubbles during in situ annealing were both characterized by transmission electron microscopy. The annealing temperature and annealing time affect the process of helium bubbles evolution and formation. Meanwhile, the grain boundaries act as sinks to accumulate helium bubbles. However, the precipitation phase seems have few effects on the helium bubble evolution, which may be due to the coherent interface and same structure of γ’ precipitation and matrix.
Highlights
Pre-Irradiated FeCoNiCrTi0.2 Alloys.Recently, high-entropy alloys (HEAs) have been regarded as one of the potential nuclear structural candidate materials due to their excellent irradiation resistance [1,2,3,4,5]
In nuclear reactors, (n, α) a transmutation reaction will produce a number of helium atoms, which are easy to precipitate at grain boundaries and dislocations, forming helium bubbles and voids, resulting in material swelling and material failure [6]
Duan et al found that the ultra-fine grained FeNiCoCr alloys remains stable under the irradiation damage up to 58 dpa in the temperature of 573 K and 773 K, which indicated that an excellent irradiation resistance of Fe-Co-Ni-Cr HEAs [13]
Summary
High-entropy alloys (HEAs) have been regarded as one of the potential nuclear structural candidate materials due to their excellent irradiation resistance [1,2,3,4,5]. Some progress has been made in the diffusion of He atoms and the growth mechanism of helium bubbles in high-entropy alloy materials [7,8,9,10,11,12]. Duan et al found that the ultra-fine grained FeNiCoCr alloys remains stable under the irradiation damage up to 58 dpa in the temperature of 573 K and 773 K, which indicated that an excellent irradiation resistance of Fe-Co-Ni-Cr HEAs [13]. Chen et al found that 1/3 dislocation loops were formed and the helium bubbles were observed under the irradiation of 275 keV He+ at
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