Observation of interstitial atoms in F.C.C. metals

Abstract

FOB a number of years, among the outstanding problems in the study of lattice defects in f.c.c. metals there have been the properties of atoms on interstitial lattice sites as produced by cold-work or radiation damage. Considering copper as an example, the key problem was whether the energy of migration of interstitial atoms was about 0–1 ev or about 0–6 ev. In the first case, the interstitial atoms would anneal out below 60°K, whereas in the second case the so-called annealing stage III (at about 250°K) would have to be ascribed to the annealing out of the interstitial atoms. So far no specific experiment has been published that would demonstrate directly the presence or the behaviour of isolated interstitial atoms in f.c.c. metals. The two views mentioned above are based on the analysis of a large body of experimental material, the interpretation of which includes the assignment of migration and formation energies to lattice defects other than interstitials. Recent reviews emphasizing the one or the other of the two principal viewpoints are those by Seitz (1959; small migration energy of interstitials) and by Seeger (1058, 1960; large migration energy of interstitials).