Modulated structure in al₆₅cu₂₀fe_15-xmnx alloys, studied by transmission electron microscopy

Features of crystal structures of AlgsGoFexMnx alloys have been investigated by transmission electron microscopy. Electron diffraction patterns obtained experimentally show that some alloys exhibit similar diffraction patterns to those of the decagonal quasicrystal, in addition to those taken from the icosahedral quasicrystal as well as the AMn and AlFe crystalline approximants. That is, there are both diffraction patterns showing a crystal period of 1. 2 nm along one direction and a pseudo-tenfold one. with an electron incidence parallel toit. From high resolution images taken in the present works, it was also found that these patterns originate from a singlestate region. These results clearly imply that a structure characterized by these patterns can be identified as a two-dimensional modulated structure, which should be distinct from not only the icosahedral and decagonal quasicrystals but also the crystalline approximants.