Trapping of self-interstitials at chromium atoms in electron-irradiated dilute AlCr alloys

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Abstract
The interaction of migrating aluminium interstitials with chromium atoms as solutes has been investigated by resistivity damage rate measurements in stage II and by isochronal recovery experiments in a series of dilute AlCr alloys. The effective trapping radii of Cr for migrating interstitials have been determined from stage I recovery suppression and from stage II damage rates by applying the diffusion theory to the data. The properties of a large recovery stage at 56K characteristic of AlCr appear to be similar to those of stage IIc found in electron-irradiated dilute Cu alloys and attributed to the final release of trapped interstitials. On the other hand, the analysis of the damage rate experiments shows that Cr traps interstitials above 56K forming two different complexes, the configuration and specific resistivity of which depend upon the irradiation temperature. The results suggest that Cr provides both shallow traps (effective below 56K) and deep traps (effective up to 200K) for mobile interstitials, and that the latter must overcome a potential barrier in order to gain access to the deep traps. The effective trapping radius of Cr is 0.47 rv at 48K and 0.15 rv, both at 80K and 120K. At these temperatures the capture radius of the chromium-one-interstitial complex is significantly larger than that of a single chromium atom, its specific resistivity being considerably lower than at 48K.