For pt.I see ibid., vol.4, p.10199 (1992). The recovery of short-range ordered Ni(Al) and Ni(Al,Ti) solid solutions and long-range-ordered Ni3Al intermetallic compounds was investigated by residual electrical resistivity measurements as a function of composition and of fluence, after low-temperature (4-9 K) irradiation with 2.95 MeV electrons. In the solid solutions, long-range defect migration resulted in increases of local order, self-interstitials were found to be mobile above 110 K (at least in the binary alloys) and vacancies to be mobile above 330 K. The recovery spectrum of irradiated intermetallic compounds showed some similarity with that of pure nickel, with a smaller amount of fine structure. The mobility of self-interstitials (corresponding mainly to Ni-Ni dumbbells) occurs at a higher temperature (75 K) than in nickel (50 K) and does not induce significant ordering. By contrast, the Ni vacancies, which are the dominant vacancy species, are slightly less mobile than in nickel and promote some increase of long-range order.

The effect of alloy composition on radiation damage by 2.95 MeV electrons at low temperature has been investigated in Ni(Al) and Ni(Al,Ti) solid solutions and in Ni3Al intermetallic compounds (24.6-26.5 at.% Al) by residual electrical resistivity measurements. In the solid solutions the main result of irradiation was point-defect production. Frenkel-pair resistivities, deduced from the comparative analysis of the initial damage rates in the solid solutions and in pure nickel, were 6.5-9.4 mu Omega cm/%, similar to or slightly larger than the value of nickel. In Ni3Al intermetallic compounds, the resistivity damage rates were enhanced by a factor of about 15 compared with pure nickel. Disordering contributes only a small part of the increase. Assuming an average of 3+or-1 replacements per displacement, a comparison of the initial damage rates in nickel and in the compounds leads to Frenkel-pair resistivities ranging from 97 to 109 mu Omega cm/%. Such high values may be correlated with the large ideal resistivity of these materials.