TEM investigations on the growth of the icosahedric phase in AlMn films produced by simultaneous deposition of the components

Thin AlMn films were grown by simultaneous deposition of the components on carbon substrates (a-C, HOPG). The films were characterized by transmission electron microscopy, electron diffraction and EDX. Depending on composition, deposition rate, and substrate temperature, different phases were found, which partly coexist. At substrate temperatures between 300 and 500°C, and at a total deposition rate of as low as 0.01 nm/s, the pure icosahedric phase developed for Mn concentrations near 14 at.%, while higher rates caused segregation of Al6Mn crystallites at 400°C. At lower Mn contents, Al was segregated, at higher deposition rates even for Mn contents up to 19 at.%. At Mn contents between 19 and 54 at.%, precipitates of Al8Mn5 were found.