Al-Mn METASTABLE PHASES PREPARED BY SOLID STATE INTERDIFFUSION AND OBSERVED BY TEM AND OPTICAL MEASUREMENTS

Overview & Synopsis

Alternate layer samples of aluminium and manganese are produced by vapor deposition on glass and NaCl substrates. Heat treatments are then performed in ultra high vacuum conditions in order to prevent the formation of an oxide layer. The samples are heated up at a constant rate of 2K per minute, then maintained during two hours at the fixed annealing temperature. The modifications induced by solid-state reaction are followed at each annealing step by transmission electron microscopy and optical reflectivity measurements. The interdiffusion begins at 220°C ; an amorphous Al1-xMnx phase starts growing at 225°C ; a crystalline phase, presumably A16Mn, is observed to grow at an annealing temperature of 230°C at the expense of the amorphous phase. Therefore in our experimental conditions (Mn concentration, thicknesses of the layers) we were not able to produce either amorphous or quasicrystalline single phase samples by solid state reaction in contrast with ion beam mixing.