The determination of rare earth alloying additives in special steels by neutron activation analysis

A procedure for neutron-activation analysis of cerium, lanthanum, praseodymium and neodymium, tested on more than thirty samples of steels, is described. After irradiation for 20 hrs with a neutron flux of 1.2x1013n cm-2s-1 the steel samples were dissolved in aqa regia and extraction separation of iron from 6N HCl by ether was employed. The rare earth elements were separated as a group by precipitation as fluorides and hydroxydes. The individual rare earth elements were separated from each other using a KU-2 cation exchange resin and a solution of ammonium α-hydroxyisobutyrate as eluant. The separated samples were counted on a NaI/Tl γ-spectrometer. More than thirty samples of steels were analysed by the method described. The calculated standard deviations for the rare earth elements contents were less than 8-14%. (T.G.)