Separation in Fe–Ni and Fe–Ni–P alloys under electron irradiation and isochronous annealing

Abstract

The annealing of radiation defects in the Fe–34.7at.%Ni and Fe–34.6at.%Ni–0.1at.%P alloys irradiated with 5 MeV electrons is studied by the method of residual electrical resistivity. It is shown that, during annealing after irradiation at 80 K, vacancies become mobile in the region of 220 K with a migration energy of about 0.6 eV. In this case, vacancy-impurity complexes (clusters) are formed, and in the H36 alloy vacancy clusters are formed. Under irradiation at room temperatures, vacancy defects accumulate in the form of vacancy clusters. The dissociation of these clusters at 350–550 K results in the appearance of freely migrating vacancies and enhanced self-diffusion. This leads to radiation-accelerated ordering processes in the Fe–Ni and Fe–Ni–P alloys. At temperatures around 800 K, homogenization of the solid solution occurs. The details and stages of the dissociation of vacancy-impurity complexes are discussed.