Stable Quasicrystalline Phase in Al-Cu-Fe-Cr Coating Materials
نویسندگان
چکیده
Transmission electron microscopy (TEM) studies have been carried out on magnetron-sputtered coatings in the Al-rich region of the Al-Cu-Fe-Cr quasicrystalline phase field, focusing on the composition that exhibited the best tribological performance among a group of sputtered coatings. The size of the particles in the as-deposited coating is around 10 nm. The TEM experiments on annealed coatings (450 8C for 6 hours 1 400 8C for 7 hours) revealed that the material is composed of a decagonal quasicrystalline phase with a periodicity of 1.24 nm along the unique axis and a hexagonal crystalline phase, with a 5 2.48 nm and c 5 1.24 nm. These results show that a thermodynamically stable quasicrystallinephase exists in theAl-Cu-Fe-Cr alloy system, in addition to previously reported microcrystalline structures and orthorhombic and monoclinic approximants. The hexagonal phase is a crystalline approximant of the decagonal phase, structurally related to hexagonal crystalline phases previously reported in Al-Mn and Al-Cr-Ni quasicrystalline alloys.
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