The study of mechanical properties of quasicrystals, in particular icosahedral Al-Cu-Fe alloys, is a topical task in materials science due to their potential use as wear-resistant coatings and functional materials. Microindentation, as a method of local mechanical action, allows one to evaluate the hardness, elasticity and plasticity of a material at the micro- and nanolevel, providing valuable information on its mechanical behavior.
The microindentation process of the icosahedral Al-Cu-Fe quasicrystal is characterized by a number of features caused by its aperiodic structure. Unlike crystals, where deformation is mainly concentrated along the slip planes, in quasicrystals deformation is distributed more uniformly, which is associated with the absence of translational symmetry.
Numerous microindentation tests of icosahedral quasicrystals (QCs) have been performed at ambient temperature. The results have shown that icosahedral QCs, in particular Al-Cu-Fe 1, 2, Al-Pd-Mn 3, 4, 5, Al-Li-Cu 6, 3, Al-Ru-Cu [3] and Mg-Zn-Y [7] alloys, are characterized by significant hardness and low crack propagation resistance. In turn, compression tests have revealed that these materials exhibit a transition from brittle fracture to plastic deformation (TFT) at approximately 0.7 Tm, where Tm denotes the melting temperature. A number of microindentation experiments have been published, performed at elevated temperatures, in both the brittle and plastic behavior regions. However, the temperature dependence of the hardness of icosahedral QDs has been studied in detail only in two cases: for Al-Li-Cu and Al-Pd-Mn.
In this paper, we present microindentation measurements obtained for an icosahedral Al-Cu-Fe alloy over a wide temperature range. The results are compared with previous studies of the same alloy using compression tests.
Analysis of the obtained indenter prints, as well as the dependence of the load on the penetration depth, allows us to identify such parameters as Vickers hardness, elastic modulus and degree of plastic deformation. An important aspect is the study of the influence of the orientation of the icosahedral structure relative to the sample surface on the results of microindentation. Different orientations can lead to anisotropy of mechanical properties, which requires detailed analysis and statistical processing of the data.
The study of microindentation of icosahedral Al-Cu-Fe contributes to a better understanding of the mechanical properties of quasicrystals and opens up prospects for their application in various fields of science and technology.
Author: E. Giacometti, N. Baluc, J. Bonneville, J. Rabier
Institute: Laboratory of Metallurgical Physics, Department of Physics, EPFL, 1015 Lausanne, Switzerland, Plasma Physics Research Center – EPFL, Fusion Materials Department, 5232 Villigen-PSI, Switzerland, Laboratory of Physical Metallurgy, University of Poitiers, SP2MI-Teleport 2-BP 179, 86960 Futuroscope Cedex, France