Radiation-induced separation of solid solution in Fe-Ni invar

摘要

Radiation-induced solid solution separation (RISSS) in the Fe-34.7 at.% Ni invar alloy was investigated by residual resistivity and linear thermal expansion coefficient (TEC) measurements. The alloy was irradiated with 5 MeV electrons at 245-570 K and isochronous annealed. It was found that RISSS leads to an increase of 20% in the residual resistivity and an increase of 10 ~(-5) K~(-1) in the TEC for an electron irradiation dose of 5 × 10~(18) cm~(-2). The kinetics of RISSS are the same, but the irradiation efficiency coefficient increases approximately by a factor of 10 when the irradiation temperature rises in the range of 240-570 K. Vacancy clusters, which are formed under irradiation, retard the decomposition. It was shown that dissociation of the vacancy clusters at temperatures of 320-500 K was followed by the free migration of the formed vacancies, and leads to further RISSS.