ROKYTSKA O. Features of formation and physical and mechanical properties of quasicrystals and their approximants in alloys of the Ti-Cr-(Me)-Al-Si-O system

The regularities of the formation of quasicrystalline and approximant phases in the Ti- Cr-(Me)-Al-Si-O system are established depending on the alloying and crystallization conditions, as well as the mechanical properties of the materials obtained. The systematic approach demonstrated in the study of materials based on the Ti-Cr-Me-Al-Si-O system containing quasicrystalline or approximant phases made it possible to reveal the regularities of obtaining an optimal set of mechanical properties. In particular, determine the correlation of chemical composition - structure - properties. The physical and mechanical properties of alloys in various structural states have been investigated for the first time. The temperature ranges of the deformation mechanisms of the Ti60Cr30Al3Si2(SiO2)5 alloy have been established and it has been determined that it has a high heat resistance in comparison with traditional titanium-based alloys, which do not work above 650С. For the first time, the method of automatic indentation was used to study the physical and mechanical properties of alloys of the Ti-Cr-Al-Si-O and Ti-Cr-Me-Al-Si-O systems. It was found that the hardness of the obtained alloys is close to the values of the theoretical hardness. A general proportionality was established between the values of H and E, which is characteristic of other quasicrystalline materials (H/E = 0.05), but the ratio for the investigated alloys with the content of the approximant phase is higher (H/E = 0.075). For the first time, an amorphous-nanocrystalline coating was obtained from the Ti60Cr30Al3Si2(SiO2)5 alloy by magnetron sputtering, it has high hardness and wear resistance and is promising for use in the form of wear-resistant, heat-resistant and thermal barrier coatings Key words: quasicrystals, approximants, phase composition, structure, indentations, hardness, coating, oxidation resistance. Підписано до друку