Effects of intermetallic nanoparticles on the evolution of vacancy defects in electron-irradiated Fe–Ni–Al material

Abstract

In this paper we study the effects of intermetallic nanoparticles like Ni3Al on the evolution of vacancy defects in the fcc Fe–Ni–Al alloy under electron irradiation using positron annihilation spectroscopy. It was shown that the nanosized (∼4.5 nm) intermetallic particles homogeneously distributed in the alloy matrix caused a several-fold decrease in the accumulation of vacancies as compared to their accumulation in the quenched alloy. This effect was enhanced with the irradiation temperature. The irradiation-induced growth of intermetallic nanoparticles was also observed in the pre-quenched Fe–Ni–Al alloy under irradiation at 573 K. Thus, a quantum-dot-like positron state in ultrafine intermetallic particles, which we revealed earlier, provided the control over the evolution of coherent precipitates, along with vacancy defects, during irradiation and annealing. Possible mechanisms of the absorption of point defects by coherent nanoparticles have been discussed too.

The effect of alloying elements on the vacancy defect evolution in electron-irradiated austenitic Fe–Ni alloys studied by positron annihilation

“…4). It was mentioned in Section 3.1 that small vacancy loops are formed mainly under irradiation at 573 K. It should be noted that the S-parameter does not recover its initial values (before irradiation) for the samples, which were irradiated at 300, 423 K and annealed at $800 K. Unfortunately, the further increase in the annealing temperature leads to thermal aging of the alloy and the localization of positrons in nanosized particles of Ni 3 Al [8]. Note also the growth of the S-parameter in the sample, which was irradiated at 573 K and annealed at 773 K (see Fig.…”

“…1-3 present the dependence of the S-parameter on the electron fluence for Fe-Ni-Al and Fe-Ni-Si alloys exposed to irradiation at 300, 423 and 573 K, respectively. The data for the Fe-NiAl alloy are taken from our previous work [8]. In [8] the quenched state of the Fe-Ni-Al alloy is designated as the Q-state.…”

“…The data for the Fe-NiAl alloy are taken from our previous work [8]. In [8] the quenched state of the Fe-Ni-Al alloy is designated as the Q-state. For comparison, Figs.…”

“…4 presents the S-parameter versus the isochronal annealing temperature of the Fe-Ni-Al and Fe-Ni-Si alloys exposed to a fluence of up to 5 Â 10 22 m À2 . The data for the Fe-Ni-Al alloy are taken from [8].…”

“…Our previous studies [8][9][10] demonstrated the effect of nanosized intermetallic precipitates (like Ni 3 Al) on the evolution of vacancy defects in a Fe-Ni-Al model alloy. This study deals with the effect of alloying elements in the solid solution.…”