Interstitial trapping in Fe-implanted Al after excimer laser annealing

Laser annealing was used to create a supersaturated solution of Fe atoms in Al, in order that channeling measurements of self-interstitial trappings could be made. A single crystal of Al was implanted with 40 keV 56Fe to a fluence of 1.6x1015 ions cm-2. A 4 mm diameter region of the crystal was annealed in air with a XeCl excimer laser at an energy density of approx.=6 J cm-2. This treatment produced a relatively perfect crystal: the normalized yield of 1 MeV He+ ions from near-surface Al atoms for <110> alignment at 35 K was 0.04. The Fe atoms were approx.=90% substitutional, corresponding to a solubility of approx.=0.3 at.%, as compared with only approx.=0.02 at.% obtained by a water quench from 873 K. The crystal was then irradiated with 1 MeV He+ at 70 K to a fluence of approx.=5x1015 ions cm-2, in order to create mobile Al self-interstitial atoms which could be trapped by the Fe atoms. A channeling analysis of the resulting displacement of Fe atoms indicated that they trapped self-interstitials strongly, as observed for other small solute atoms in Al. As no flux peaking in the backscattering yield from Fe atoms was observed for a <110> angular scan, the results indicate that the trapping configuration may differ from that observed for Cr, Mn or Cu solute atoms in Al. The trapped interstitials were annihilated by vacancy migration near 200 K. (orig.)