Decomposition of the MANET steel was observed by means of atom probing
after 300 keV Fe+ ion irradiation to 50 dpa and simultaneous implanta
tion of 15 keV He+ ions at a rate of 200 appm/dpa. At irradiation temp
eratures of 673 and 698 K weak periodical variation of the chromium co
ncentration was observed. At irradiation temperatures of 723 and 773 K
clusters with chromium concentration of up to 25 at% were detected.