Author: Yu.V. Milman, M. O. Efimov, A. A. Golubenko, Wang Changliang, Li Zhang, Zhu Chonggao & Tian Haoliang
Institute: Institute for Problems of Materials Science named after. Frantsevich National Academy of Sciences of Ukraine, Kyiv, Ukraine, Key Laboratory of Aviation Science and Technology on Advanced Corrosion and Protection of Aviation Materials, Beijing Institute of Aviation Materials, Beijing, 100095, China
Quasicrystalline materials are a class of materials that exhibit an atomic ordering that is different from the normal crystalline structure. They are characterized by high hardness, strength and corrosion resistance. One such material is a quasicrystalline Al-Cu-Fe coating.
Quasicrystals are a special type of structure that has amazing physical and chemical properties. They are composed of periodic but non-repeating unit cells, the symmetry of which is forbidden in three-dimensional space. Such irregular crystal structures are a sequence of atoms organized according to a specific algorithm that does not obey the usual laws of crystallography. The study of the thermochemical stability of quasicrystals plays an important role in understanding their behavior under various conditions.
To achieve this goal, the microindentation method was used to study the mechanical behavior of quasicrystalline al63cu25fe12 coatings in the temperature range from 77 to 1073 K. Coatings with a thickness of 350 μm were obtained by high-speed air-fuel spraying of powders 40-80 μm in size atomized in water onto a 45 steel substrate After production, the content of the icosahedral quasicrystalline phase in the coatings was 75 wt.%. After annealing at 998 K for 20 minutes, it was possible to obtain a coating with a 100% quasicrystalline phase. The microhardness of the studied coatings at a temperature of 77 K and room temperature (293 K) is about 7 GPa and decreases slightly to a level of about 4.5 GPa at a temperature of 725 K, and then sharply drops to 1.5-1 GPa at temperatures of 923-973 K An analysis of the dependence of temperature on plasticity, determined by the indentation method, showed that up to 873 K, quasicrystalline coatings of the al-cu-fe system are brittle when tested in compression/tension, and above 873 K they begin to exhibit macroplasticity. Calculation of ductility values over a wide temperature range makes it possible to predict the mechanical properties of quasicrystalline coatings of the al-cu-fe system, which are brittle under standard test methods.
As a result of the study, valuable data were obtained on the mechanical properties of quasicrystalline Al-Cu-Fe coatings over a wide temperature range. These materials have been found to be highly resistant to wear and damage at low and high temperatures, making them attractive for use in extreme environments. Moreover, the study made it possible to identify the main patterns between the mechanical properties of coatings and temperature conditions, which makes it possible to optimize and improve their use in various fields of science and technology.