The purpose of this study is to investigate the elastic properties of thermally aged Fe-Cu model alloys by the electromagnetic acoustic resonance (EMAR) method and to clarify the underlying mechanism. Fe-lwt.%Cu alloys, in supersaturated Cu solid solution, were prepared. The specimens were isothermally aged at 773K up to 10^4 min and isochronally aged for 30 min up to 973K. Resonant ultrasound spectra were obtained in both aging procedures. The aging time dependence of resonance frequencies of isothermally aged specimens, which relates to the elastic constants, showed an increasing behavior. This is different from the peaking trend of the hardness and attributable to the increase of the elastic constant due to Cu solute depletion in the matrix during the precipitation process. This study suggests the possible application of the EMAR method for nondestructive characterization of the matrix state of irradiated RPV steels.
