Effect of Electronic Energy Dissipation on Strain Relaxation in Irradiated Concentrated Solid Solution Alloys

The effect of energy deposition by energetic particles on Ni and two single-phase concentrated solid solution alloys (NiFe and NiCoCrFe) is investigated through combined experimental and modelling efforts. Damage evolution as a function of increasing ion fluence is monitored via elastic strain developed in the irradiated crystals. We show that damage produced from displacement collision cascades is sensitive to subsequent highly ionizing irradiation that the strain generated by elastic nuclear collisions undergoes partial relaxation upon high-energy irradiation. This finding indicates a change in the damage structure upon electronic energy deposition due to both predominant defect annealing and growth of small defect clusters. Strain relaxation, more pronounced in the alloys than in Ni, is ascribed to both higher thermal conductivity and weaker electron-phonon coupling in Ni.