Münster 1999 – scientific programme

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M: Metallphysik

M 13: Atomare Fehlstellen

M 13.8: Talk

Tuesday, March 23, 1999, 12:00–12:15, S 6

On the Formation of Agglomerates of Interstitials in FCC Materials — •W. Sch"ule — Institut f"ur Angewandte Physik der J. W. Goethe-Universit"at Frankfurt, D-60054 Frankfurt

The formation of agglomerates of interstitials has been investigated in many fcc materials by means of radiation-enhanced diffusion using mainly electrical resistivity techniques. It was found that agglomerates of interstitials are formed below the recovery stage IV temperature region. Their dynamic steady state concentrations are obtained after relatively short irradiation times increasing with decreasing irradiation temperature. The size of the agglomerates of interstitials increases continuously with increasing time. The size of the agglomerates of interstitials increases continuously with irradiation time below about 100^∘C below the recovery stage IV temperature region. The very small agglomerates of interstitials annihilate in (-copper-zinc alloys during a subsequent annealing at ca 160^∘C with an activation energa of Q1 = 1.6 eV and the larger agglomerates of interstitial annihilate at ca 230^∘C with an activation energy of Q2 = 2.2 eV, which is the activation energy of self-diffusion. The transition temperature, below which agglomerates of interstitials are formed, is also the transition temperature for the formation of agglomerates of vacancies, which are formed above this temperature, however, only after very long irradiation times. The finding, that agglomerates of interstitials are formed during irradiation at high temperatures, i.e. below the recovery stage IV temperature region, is only compatible with the assumption that the modified two-interstitial model is the correct radiation damage model according to which interstitials migrate in the recovery stage III temperature region.