Al-Cu-Fe quasicrystals are a unique class of materials with unusual physical and chemical properties due to their aperiodic structure. Unlike crystals, where the atoms are arranged in a strictly repeating order, quasicrystals exhibit long-range order but without translational symmetry. This leads to interesting phenomena such as high hardness, low thermal conductivity, and unique electronic properties.
One of the most interesting aspects of the study of quasicrystals is the possibility of their continuous transformation through structural changes. These changes can be caused by various factors, including heat treatment, mechanical action, or alloying with other elements. As a result, a gradual change in the atomic structure of the quasicrystal occurs, leading to a modification of its properties.
The study of continuous transformations of Al-Cu-Fe quasicrystals is important for understanding the fundamental aspects of their structure and properties, as well as for developing new materials with specified characteristics. Controlled changes in the structure of quasicrystals open up prospects for creating materials with improved mechanical, thermal and electronic properties, which can find application in various fields of science and technology.
In the AlCuFe quasicrystalline structures with icosahedral symmetry, two different types of smooth structural changes were observed. In the case of Al65Cu20Fe15, a transformation into a rhombohedral approximating phase occurs; this process is characterized by spatial homogeneity and is expressed as a uniform shift of the diffraction reflections. In contrast, the Al60Cu30Fe10 quasicrystals show a tendency to separate into two different rhombohedral approximations through localized structural rearrangements, predominantly along the fivefold symmetry axes. This leads to the appearance of pronounced diffuse scattering and twist contrast. The described transformations can be considered as a result of phase deformations of the crystal lattice.
Author: W. Liu, U. Koster
Institute: Department of Chemical Engineering, University of Dortmund, W-4600 Dortmund 50, Germany