Nanomechanical characterization of Al–Co–Ni decagonal quasicrystals

Abstract

This paper addresses some issues related to the nanomechanical responses of decagonal quasicrystals using nanoindentation techniques. A Hysitron Triboscope with a Berkovich indenter was used to carry out the nanoindentation tests on single crystals of Al–Co–Ni decagonal phase. The anisotropy in terms of nanohardness at higher load was observed, whereas it was not possible to establish the same at lower loads. However, the Young's modulus was found to be indistinguishable in all these cases. Discontinuity in load displacement, which is known as a ‘pop-in’ effect, was observed frequently at various load regime. It was found that this discontinuity was not due to cracking or a phase transformation effect, but to a plastic yielding phenomena and nanodeformation of the material. Significant differences between the nanohardness and microhardness were noticed and are discussed based on various experimental parameters and the consequent mechanical response of materials.

Acknowledgements

We would like to thank Dr S. V. Sarma (IFW Dresden) for stimulating discussions and for his help in microindentation and SEM observations. One of the authors (NKM) acknowledges the Research Fellowship provided by the Alexander von Humboldt Foundation, Germany. The partial support of Department of Science and Technology (DST), India, is also gratefully acknowledged.