Positron annihilation spectroscopy characterization of effect of intermetallic nanoparticles on accumulation and annealing of vacancy defects in electron-irradiated Fe-Ni-Al alloy

• Published in: Philosophical magazine (Abingdon, England) Vol. 88; no. 6; pp. 959 - 976
• Main Authors: Druzhkov, A.P., Perminov, D.A., Pecherkina, N.L.
• Format: Journal Article
• Language: English; Russian
• Published: Abingdon Taylor & Francis Group 21.02.2008; Taylor and Francis
• Subjects: electron irradiation; fcc alloys; nanoparticles; positron annihilation; vacancy defects
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430802014670

The effect of intermetallic nanoparticles like Ni 3 Al and nanoparticles of an Fe-rich bcc phase on the evolution of vacancy defects in an fcc Fe-34.2 wt% Ni-5.4 wt% Al model alloy under electron irradiation at elevated temperatures (423 and 573 K) was investigated using positron annihilation spectroscopy. Nanosized (1-8 nm) particles, which are homogeneously distributed in the alloy matrix, cause a several-fold decrease in the accumulation of vacancies as compared to their accumulation in a quenched alloy. This effect depends on the size and the type of nanoparticles. The effect of the nanoparticles increases when the irradiation temperature increases. The irradiation-induced nucleation and the growth of intermetallic nanoparticles were also observed in an alloy pre-aged at 1023 K under irradiation at 573 K. Thus, a quantum-dot-like positron state within ultrafine intermetallic particles, which we revealed earlier, allows control of the evolution of coherent precipitates like Ni 3 Al, along with vacancy defects, during irradiation and subsequent annealing. Possible mechanisms of the absorption of point defects by nanoparticles are discussed.