In order to investigate the effects of helium on t he phase
stability and micro structural evolution in aged Fe-Cr-Mn alloy
durin g modes of electron beam and electron/ He +-ion dual-beam, in-site obser vation were carried out using a high voltage electron microscope connected with an ion accelerator,the effect of helium on the phases
stability is appraised. E xperimental results show that the low density of void were formed on the phase b oundaries by electron
irradiation only. The damage structure had synergistic eff ect during electron/ He +-ion dual-beam irradiation. The change of phase stability were quickened. Example: radiation induced precipitate was grown due t o diffusion of solute atom, new phase were formed which not formed in aging trea tment alloys. The atomic mixing and the radiation disordering promote the modifi cation of precipitated phases. The effect of interaction between helium and poin t defects and solute atom, and the change reason of phase stability were discuss ed.