Deposition of coatings containing quasicrystalline AlCuFeB and β phase by magnetron sputtering

It is known that quasicrystals show interesting material properties like a reduced surface energy, low adhesion and a low coefficient of friction. One quasicrystal which is an equilibrium phase and which is of special interest due to the low cost of the constituents is Al59Cu25.5Fe12.4B3. AlCuFeB coatings were deposited on different substrates by magnetron sputtering. All targets used were produced at the RHP-Technology GmbH by uniaxial hot pressing, using different powders. The targets show ceramic behavior like low electrical and thermal conductivity as well as high brittleness, which is probably due to the developed quasicrystalline phase. For deposition, the following parameters were varied: deposition power, working gas pressure, post annealing parameters. The deposited coatings were analyzed by high resolution scanning electron microscope (HRSEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The targets suffer from crack formation which results in statistical deviations in the coating composition and a systematic dependence of the coating composition on the working gas pressure and deposition power. It could be shown that a quasicrystalline AlCuFeB phase develops if the chemical composition is close enough to the nominal Al59Cu25.5Fe12.4B3 composition and if appropriate post annealing parameters are chosen.