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

Abstract Plastic deformation of the quasicrystalline decagonal phase Al₇₂Co₉Ni₁₉, 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 Al₃(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)