The study compares impressions into one and the same single-quasicrystallin
e Al70Pd20Mn10 sample (surface of fivefold symmetry) that were performed by
spherical and pointed indenters (Vickers- and corner-of-a-cube-geometry) a
nd investigated using Atomic Force Microscopy (AFM). The Meyer hardness num
ber was found to vary with indentation size in a manner similar to material
s that work harden, though this behavior must have a different physical ori
gin: for spherical indentations the hardness number slightly increases with
increasing load (Meyer hardness evolution), whereas for pyramid-shaped ind
enters a considerable hardness increase in case of decreasing load can be s
tated. Spherical indentations show little piling-up only in contrast to poi
nted indentations where huge elevations surrounding the indent developed. D
ifferent degrees of lateral cracking can account for this observation. In c
ase of Vickers indentations the material breaks into segments which display
mutual shearing. Distinct differences can also be noticed with respect to
the volume balance between the apparent piled-up volume around the impressi
on and the volume of the displaced material. This balance proves positive f
or pyramidal and negative for spherical impressions. (C) 2000 Kluwer Academ
ic Publishers.