High temperature radiation damage in binary bcc Fe alloys containing 1 atomic % Au or Cu due to Fe ion irradiation at 550 °C to a peak dose of 2.8 and 8.3 dpa is studied. The precipitation behavior of gold and copper and its correlation to the irradiation-induced defects is studied by transmission electron microscopy and variable energy positron annihilation spectroscopy (VEPAS). The increase of S parameters from VEPAS indicates the formation of open volume defects upon irradiation. Disc-shaped Au precipitates, grown from the irradiation induced dislocations, are observed in the Fe-Au alloy. In the Fe-Cu alloy, spherical Cu particles are formed but no direct connection between Cu precipitates and radiation damage is detected. For the Fe-Au alloy, the surface hardness dramatically increases for a dose of 2.8 dpa, with a slight decrease as the irradiation dose is enhanced to 8.3 dpa. In the Fe-Cu alloy, radiation hardening increases continuously.@en