화학공학소재연구정보센터
Journal of Materials Science, Vol.35, No.3, 723-734, 2000
A comparison of indentations of different size and geometry in single-quasicrystalline AIPdMn
The study compares impressions into one and the same single-quasicrystalline Al70Pd20Mn10 sample (surface of fivefold symmetry) that were performed by spherical and pointed indenters (Vickers- and corner-of-a-cube-geometry) and investigated using Atomic Force Microscopy (AFM). The Meyer hardness number was found to vary with indentation size in a manner similar to materials that work harden, though this behavior must have a different physical origin: for spherical indentations the hardness number slightly increases with increasing load (Meyer hardness evolution), whereas for pyramid-shaped indenters a considerable hardness increase in case of decreasing load can be stated. Spherical indentations show little piling-up only in contrast to pointed indentations where huge elevations surrounding the indent developed. Different degrees of lateral cracking can account for this observation. In case 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 impression and the volume of the displaced material. This balance proves positive for pyramidal and negative for spherical impressions.