Structural transformations in heat resistant coatings containing rare earth elements

Degradation of two-layered coatings and ZhS6U alloy microstructure were studied during long-term processes of high temperature annealing and creeping. It was shown that yttrium and zirconium oxides are promising as protective coatings for heat resistant nickel based alloy

Study of the microstructure of synthesized laminates

The studies show the possibility of obtaining titanium - titanium aluminide laminates by the interaction of titanium with aluminum. An important role in the study and obtaining of such materials is assigned to the study of diffusion processes between titanium and aluminum layers, and the formation of intermetallic layers and their microstructure. In the experiments the desired laminated microstructure is obtained by all four methods. At the same time, the disadvantages inherent in each of these methods are found. Ti- Al3Ti metal - intermetallic laminates synthesized by thermal explosion, reaction sintering with and without pressure, explosion welding with further heat treatment for powder mixtures and foils are studied using a microstructural analysis. The structure and composition of the samples are studied by X-ray diffraction, X-ray microanalysis, and metallography. The best microstructural parameters are obtained by explosion welding of a multilayer package of titanium and aluminum plates, then by sintering this package in a muffle furnace with selection of time-temperature parameters. The conducted studies can be used to obtain laminates with a desired thickness of titanium and intermetallic layers

The influence of scandium on the composition and structure of the Ti-Al alloy obtained by "Hydride Technology"

In this study the influence of scandium on the structural and phase state of the Ti-Al alloy obtained by the method of “Hydride Technology” (HT). The Rietveld method has allowed for determining the content of basic phases of the 49at.%Ti-49at.%Al-2at.%Sc system. By means of the methods of transmission electron microscopy (TEM) and X-ray spectral microanalysis, it has been established that scandium additives into the Ti-Al system result in the change of the quantitative content of phases in local regions of the structure. The Ti2Al5 phase has been found, and Ti2Al has been absent. In the morphology of substructures Ti-Al and Ti-Al-Sc there are lamellar structures or lamellae; the peculiarities of the distribution, fraction and size of which are influenced by scandium additives. The average width of Al-rich lamellae has been 0.85 U+03BCm, which is four times greater than that for the Ti-Al system (0.21 U+03BCm). For Ti-rich lamellae of the sample of the Ti-Al-Sc alloy, the average width of the lamellae has been 0.54 U+03BCm, and for Ti-Al it has been 0.34 U+03BCm. Based on the obtained data, a scheme of the distribution of phases in the composition of the Ti-Al-Sc alloy in the lamellar structures has been proposed. It has been established that in the Ti-Al-Sc system there is growth of the near-surface strength relative to Ti-Al. In this way, the microhardness of the Ti-Al-Sc alloy has amounted to 1.7 GPa, that is of the Ti-Al alloy which is 1.2 GPa

Structural transformations in heat resistant coatings containing rare earth elements

Degradation of two-layered coatings and ZhS6U alloy microstructure were studied during long-term processes of high temperature annealing and creeping. It was shown that yttrium and zirconium oxides are promising as protective coatings for heat resistant nickel based alloy

Self-propagating high temperature synthesis of TiB2-MgAl2O4 composites

Metal borides are widely used as heat-insulating materials, however, the range of their application in high-temperature conditions with oxidative medium is significantly restricted. To improve the thermal stability of structural materials based on titanium boride, and to prevent the growth of TiB2 crystals, additives based on alumina-magnesia spinel with chemical resistant and refractory properties have been used. The aim of this work is to study the structure of TiB2 with alumina-magnesia spinel additives obtained by self-propagating high-temperature synthesis (SHS). TiB2 structure with uniform fine-grained distribution was obtained in an MgAl2O4 matrix. The material composition was confirmed by X-ray diffraction analysis (DRON-3M, filtered Co kα-emission), FTIR spectroscopy (Thermo Electron Nicolet 5700, within the range of 1300–400 cm⁻¹), and scanning electron microscopy (Philips SEM 515). The obtained material represents a composite, where the particles of TiB2 with a size of 5 µm are uniformly distributed in the alloy of alumina-magnesia spinel