“…In particular, the study of various image areas (Fig. 2b) reveals that titanium-cobalt nitride Ti 0.7 Co 0.3 N almost completely covers the entire "core-shell" structure, including Based on the results of experimental studies and previously published findings [18], it can be noted that the formation of metastable nitrides with a hexagonal crystal structure, which is complexly substituted in the metal sublattice, one of which is Ti 0.7 Co 0.3 N, takes place during high-speed crystallization with an excessive amount of cooling gas (N 2 ). In terms of colloidal-chemical regularities, in the process of crystallization of nanocrystalline "core-shell" TiN-Co structures, it is necessary to take into account the absence of mutual wettability effects between complete titanium nitride and metals of the iron subgroup under equilibrium conditions created by vacuum heating.…”
Section: Resultsmentioning
confidence: 52%
“…Later, nanocrystalline Ti 0.7 Ni 0.3 N with a cubic modification was obtained and certified by X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) [17]. In [18], plasma-chemical synthesis of titanium nickelide was carried out according to the plasma recondensation scheme in a low-temperature nitrogen plasma. In the fraction from the filter, a nanocrystalline composition TiN-Ni was recorded and certified, which included a similar nitride Ti 0.7 Ni 0.3 N. The HRTEM studies showed that the nanocrystalline composition was a "core-shell" structure.…”
“…In particular, the study of various image areas (Fig. 2b) reveals that titanium-cobalt nitride Ti 0.7 Co 0.3 N almost completely covers the entire "core-shell" structure, including Based on the results of experimental studies and previously published findings [18], it can be noted that the formation of metastable nitrides with a hexagonal crystal structure, which is complexly substituted in the metal sublattice, one of which is Ti 0.7 Co 0.3 N, takes place during high-speed crystallization with an excessive amount of cooling gas (N 2 ). In terms of colloidal-chemical regularities, in the process of crystallization of nanocrystalline "core-shell" TiN-Co structures, it is necessary to take into account the absence of mutual wettability effects between complete titanium nitride and metals of the iron subgroup under equilibrium conditions created by vacuum heating.…”
Section: Resultsmentioning
confidence: 52%
“…Later, nanocrystalline Ti 0.7 Ni 0.3 N with a cubic modification was obtained and certified by X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) [17]. In [18], plasma-chemical synthesis of titanium nickelide was carried out according to the plasma recondensation scheme in a low-temperature nitrogen plasma. In the fraction from the filter, a nanocrystalline composition TiN-Ni was recorded and certified, which included a similar nitride Ti 0.7 Ni 0.3 N. The HRTEM studies showed that the nanocrystalline composition was a "core-shell" structure.…”
“…This indicates the instability of the system with these alloying elements in it. The decomposition of such system has previously been studied both for Ni 41 – 43 and Pd 44 , 45 with rich N environment, and nitride of both (Ni, Pd) has been recognized as a metastable compound. Figure 3 Comparison of the size of atom and the energy in 5 d -impurities.…”
In this work, we studied the energetics of diffusion-related quantities of transition-metal impurities in TiN, a prototype ceramic protective coating. We use ab-initio calculations to construct a database of impurity formation energies, vacancy-impurity binding energies, migration, and activation energies of 3d and selected 4d and 5d elements for the vacancy-mediated diffusion process. The obtained trends suggest that the trends in migration and activation energies are not fully anti-correlated with the size of the migration atom. We argue that this is caused by a strong impact of chemistry in terms of binding. We quantified this effect for selected cases using the density of electronic states, Crystal Orbital Hamiltonian Population analysis, and charge density analysis. Our results show that the bonding of impurities in the initial state of a diffusion jump (equilibrium lattice position), as well as the charge directionality at the transition state (energy maximum along the diffusion jump pathway), significantly impact the activation energies.
“…Это характеризуется преимущественной ориентацией кристаллической решетки, в соответствии с [20], что может быть обеспечено высокой скоростью кристаллизации получаемых порошков. Вопросы практического получения и идентификации Ti 0,7 Ni 0,3 N на примере структуры «ядро-оболочка» TiN-Ni, исследованной в рамках просвечивающей электронной микроскопии высокого разрешения, изложены в работе [21]. Фаза TiO 2 рутильной модификации формируется в процессе принудительного подкисления путем медленного натекания воздуха в классификаторы 1 и 2, ее доля составляет 2 мас.…”
Section: результаты и их обсуждение результаты и их обсуждениеunclassified
In this paper, we studied the formation of ultrafine and nanocrystalline core–shell structures based on refractory compounds of titanium with nickel during plasma-chemical synthesis of a mechanical mixture of TiC and TiNi in a low-temperature nitrogen plasma. Cooling took place in an intensely swirling nitrogen flow in a quenching chamber. The derived products were separated in a vortex-type cyclone and a bag-type fabric filter. After processing, the products were subjected to encapsulation aimed at reducing the pyrophoricity for long-term storage of the resulting finely dispersed powders under normal conditions. X-ray diffraction and high-resolution transmission electron microscopy were used to study the resulting powder products of plasma-chemical synthesis, and density measurements were conducted. Additionally, to define the average particle size more accurately, the specific surface was measured using the BET method. The instrumental research revealed the presence of ultra- and nanodispersed particles with a core–shell structure in the powder products. These particles included titanium carbide-nitride compounds as a refractory core and metallic nickel as a metallic shell. In addition, the presence of complex titanium-nickel nitride Ti0.7Ni0.3N was recorded. According to direct measurements, the average particle size of the nanocrystalline fraction is 18.9 ± 0.2 nm. The obtained research results enabled us to develop a chemical model of crystallization of TiCxNy–Ni core–shell structures, which is implemented in a hardening chamber at a crystallization rate of 105 °С/s. To fabricate the model, we used the reference data on the boiling and crystallization temperatures of the elements and compounds being a part of highly dispersed compositions and recorded by X-ray diffraction, as well as the ΔG(t) dependences for TiC and TiN.
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