In this work, the effect of induction aging on the microstructure and the hardness of a cast superalloy, Udimet500, is investigated. The solution samples were aged in two different furnaces, namely, induction furnace and resistance tube furnace, at 850°C up to 2 hours. The age-hardening behavior and microstructural characteristics were studied by hardness testing, scanning electron microscopy (SEM), electron image analyzing, X-ray diffractometery, electrolytic extraction and light laser scattering (LLS). The results show differences in the distribution of precipitates in the two groups of samples, while showing formation of tertiary fine precipitates in both groups. Formation of these fine precipitates appears to have an influence on the mechanical properties of the material. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]