An interpretation of defect production and annealing throughout stage II in dilute Ag(Cu) alloys

The experimental results presented in the previous paper (see ibid., vol.14, p.1379, 1984) are analysed with a simple chemical rate model for the damage production above stage I. It is assumed that the trapping of a second interstitial (i), an impurity-interstitial complex (ti), is a shallow trapping for which the resistivities are additive. Several assumptions are tried for the specific resistivity retained per trapped single interstitial, rho F t (i). The one which leads to the best consistency yields rho F t (i)=(160+or-10) mu Omega cm if one takes the Frenkel pair specific resistivity, rho F =200 mu Omega cm. The fact that rho F t (i) is found to be smaller than rho F is an indication of deep trapping: a mixed dumbbell is formed, as expected. A corresponding value of the trapping radius, relative to the capture radius by a vacancy is found: R t =r t /r v =0.2-0.3, which depends little on the temperature. The recovery spectra show that the mixed dumbbell Ag-Cu becomes mobile at about 120K. During its long-range migration it may either annihilate with a vacancy or combine with a second copper atom. The decrease in the resistivity which is found to correspond to this latter possibility leads us to assume that a dumbbell Cu-Cu can be formed, which is stable up to higher temperature.