Magnetic study of zircaloy. Pt. 2

Although the β-phase of Zircaloy-4 has been reported to be a supersaturated solid solution with additives, such as iron, chromium, nickel, and so forth, we have found that Zircaloy-4 after β-heat treatment is in a superparamagnetic state which contains ferromagnetic intermetallic precipitates so small (1.0-2.0 nm) that they can not be detected by usual methods. Zircaloy with additive of niobium was also found to be in a superparamagnetic state caused by the precipitates of ferromagnetic intermetallic compounds. The intermetallic compounds are a quaternary (Zr1-xNbx)(Fe1-yCry)2 as well as (Zr1-xNbx)Fe2 and Zr(Fe1-xCrx)2. Magnetic measurements of susceptibility and magnetization were carried out on Zircaloy-Nb before and after heat treatments at 0.5 to 7 kG from temperature of liquid nitrogen to room temperature. Magnetization curves scaled to saturation magnetization can be fitted closely with the calculated Langevin function. The diameter of precipitates evaluated from the graphic analysis range from 10-12 nm. (orig.)