As-cast　and　rapidly　solidified　alloys　with　compositions　of　Al70-xNi25+xRu5　(x　=　0,　5,　10　and　15)　and　Al70+yNi20-yRu10　(y　=　0　and　5)　were　examined　by　transmission　electron　microscopy.　The　results　show　that　the　Al-Ni-Ru　icosahedral　quasicrystal,　which　belongs　to　the　F-type　class,　and　the　decagonal　quasicrystal　with　a　0.4　nm　periodicity　can　coexist　in　both　the　as-cast　and　rapidly　solidified　states.　By　means　of　high-resolution　electron　microscopy　observations,　the　structural　features　of　the　as-cast　Al-Ni-Ru　icosahedral　quasicrystal　and　the　coexisting　decagonal　quasicrystal,　with　basic　quasiperiodic　order,　were　revealed.　(C)　2004　Elsevier　B.V.　All　rights　reserved.