Fast-neutron irradiation experiments were performed on a series of solution-treated, aged, and cold-worked copper-rich Cu-Fe alloys. The results obtained by electrical and magnetic measurements confirm data reported earlier that fast-neutron irradiation can cause aging or re-solution depending upon the pre-irradiation condition of the sample. The results obtained on the aged alloys are consistent with a displacement spike model, where the calculated value for the spike radius is approximately 35 Å (15 000 atoms).