The impact of nanoindentation at room temperature upon the real structure of decagonal AlCoNi quasicrystals

Plastic deformation of the quasicrystalline decagonal phase Al 72 Co 9 Ni 19 , which appears macroscopically brittle at room temperature, has been performed by nanoindentation. Employing high resolution transmission electron microscopy it could be shown that near indents regions of a nanocrystalline phase appeared, which was identified as trigonal Al 3 (Ni,Co) 2 . So, for permanent deformation at room temperature no dislocation movement was needed. Instead, it seems reasonable to assume that the decagonal phase tends to decompose into a crystalline phase under stress. Values of nanohardness and elastic modulus determined during this work were found within the range of data reported so far by other authors. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)