Positron beam Doppler broadening spectra and nano-hardness study on helium and hydrogen irradiated RAFM steel

The reduced activation martensitic steel was irradiated with 250 keV He2+ to 3000 appm and 130 keV H+ to 15,000 appm alone and in sequence at 450 degrees C. The S-W curve obtained by the positron beam Doppler broadening spectra reveals that (He, H)-V complexes were induced by irradiation. The S parameters show that the H irradiation can decrease defects by forming H-V complexes. The He irradiation can form He-V complexes and the sequentially implanted H can accelerate the formation of (He, H)-V complexes. Hardening induced by He+H sequential irradiation is greater than that by He or H ion irradiation alone, suggesting synergistic effects of He and H on defects and hardening. (C) 2014 Elsevier Ltd. All rights reserved.