Stability of the periodic decomposition structure in Cu-Ni-Fe alloys under irradiation

The influence of irradiation on the morphology and kinetics of decomposition of Cu-Ni-Fe alloys within the miscibility gap has been investigated. These alloys decompose into a periodic two phase structure with a characteristic length which can be controlled by thermal treatment to between 2 and 20 nm. The paper treats the relevance of the primary knock-on energy for the irradiation effect on the decomposition structure and kinetics. The alloys were irradiated with 150 keV protons and 300 keV Cu+ ions. The irradiation effect consisted of an enhancement of the decomposition rate for the proton case and resolution of the unmixed state for Cu ions. A model for the radiation effects considers radiation enhanced diffusion as the cause for unmixing of the alloy and cascade mixing as the cause for resolution of the unmixed state. Quantitative evaluation of the data yields an effective spheric volume of precipitate resolution having a radius of 2.6 nm. (orig.)