QUASI-CRYSTALLINE PHASE-FORMATION IN THIN-FILMS

The phenomena of reactive diffusion developing the icosahedral quasicrystalline structure (i-QC) has been analysed in the Al-Mn thin film system prepared by sequential deposition of Al and Mn at the reaction temperatures (HTSD). The development of Kirkendall voids in the Al film indicates that Al is the dominant diffusion component and that growth takes place on the top surface of the QC layer were Mn deposited. Al has a high diffusion rate across the QC layer and depends on the local structure of the QC phase. The reaction rate of Al and Mn is large if Mn is present in vapour phase while it is extremely small at the interface of QC-Mn layers, during the heat treatment of Al-QC-Mn layer system. A concentration profile of Al has been proposed for the reactive diffusion taking place in the case of HTSD.