On the determination of trapping radii of self-interstitials by impurities in dilute alloys

An explanation is given of the discrepancy which is observed in aluminium between the value of R1 (equal to rt/rv, the ratio of the capture radius of a self-interstitial atom (SIA) by an impurity to that by a vacancy) determined by radiation damage rate measurements performed above stage I and by a kinetic analysis of stage I recovery for low-temperature irradiated samples. It is shown that the multiple trapping ceases to be negligible in the damage rate method as soon as the induced defect concentration, C1, becomes significant compared to the trapping impurity concentration, C1, i.e. as soon as C1>or=R1C1/10. The effect of the multiple trapping is more important when rt is low compared to ri, the capture radius of a SIA by another SIA.