Observation of triangular loops at a twin boundary in electron irradiated high purity aluminium

Triangular shaped dislocation loops are observed at a twin boundary in an aluminium thin foil after electron irradiation at room temperature. The irradiation was performed inside an electron microscope with the energy of electrons, 200 kV. It is found that the triangular loops grow linearly with the irradiation time. The growth rate depends on the depth position of the loops inside the foil. The observed configuration of the loops is the same on both sides of the twin boundary. The results are discussed on the basis of recent model for interstitial loop growth in a thin foil, and in terms of different nucleation processes of interstitial loops at a twin boundary. (author)