ELECTRON-BEAM-INDUCED STRUCTURE TRANSFORMATION OF THE QUASI-CRYSTALLINE PHASES OF THE AL62CU20CO15SI3 ALLOY

Some details on the phase transformation experienced by the quasicryst alline phases of the Al62Cu20Co15Si3 alloy under a 400 kV electron bea m are given. The transition is observed in situ with a high resolution electron microscope and recorded on video tape. The results show that the electron beam radiation produces a sequence of changes similar to the ones observed in an ion-beam-induced amorphization process. Consi dering electron radiation damage analysis, the results agree well with the ''flip-flop'' model [Coddens, Bellisent, Calvayrac and Ambroise ( 1991) Europhys. Lett. 16, 271] where the transition from a quasicrysta lline phase to a crystalline phase is produced by atomic displacements but not in a cascade way.