Ordering effects on the microstructure and microhardness of nonstoichiometric titanium carbide TiCy

Zueva, L. V.; Lipatnikov, V. N.; Гусев, А. И.

doi:10.1007/bf02758424

Cited by 12 publications

(4 citation statements)

References 7 publications

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“…A high carbon vacancy concentration can lead to accelerated densification and excessive grain growth and consequently affect the properties of MC 1−x . [28][29][30] A similar phenomenon was observed in the high-entropy carbide system. With a carbon vacancy concentration of 30%, (Ti 0.2 Zr 0.2 Nb 0.2 Ta 0.2 Mo 0.2 )C 1−x ceramics exhibited an average grain size of 4.36 μm, which increased 51% than that of the stoichiometric (Ti 0.2 Zr 0.2 Nb 0.2 Ta 0.2 Mo 0.2 )C ceramics.…”

Section: Introductionsupporting

confidence: 70%

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Lattice rigidity in high‐entropy carbide ceramics with carbon vacancies

Liu

Guo

et al. 2023

J Am Ceram Soc.

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Due to the presence of core effects of high‐entropy materials, it is believed that the impact of carbon vacancy in high‐entropy carbides may differ from that of transition metal monocarbides. In this work, nonstoichiometric high‐entropy carbides (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C1−x (HEC1−x) with variable carbon vacancy concentration were fabricated by spark plasma sintering using powder mixtures of high‐entropy carbide and metallic powders. Compared with the corresponding monocarbides, the decline rates of lattice constant and elastic modulus were obviously slower as carbon vacancy concentration increased, indicating a more rigid crystalline lattice in the high‐entropy carbide. The valence electron number for HEC1−x ceramics with the highest hardness is 7.6, which is inconsistent with the theoretically predicted value of 8.4 for the traditional transition metal carbides. When the carbon vacancy concentration in HEC1−x ceramics is above 20%, the promoting effect of carbon vacancy on grain growth will outweigh the inhibiting effect of sluggish diffusion on grain growth, causing grains to grow quickly.

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Section: Introductionsupporting

confidence: 70%

“…Additionally, carbon vacancy can also affect the mass transport in MC 1− x ceramics. A high carbon vacancy concentration can lead to accelerated densification and excessive grain growth and consequently affect the properties of MC 1− x 28–30 . A similar phenomenon was observed in the high‐entropy carbide system.…”

Section: Introductionmentioning

confidence: 58%

Lattice rigidity in high‐entropy carbide ceramics with carbon vacancies

Liu

Guo

et al. 2023

J Am Ceram Soc.

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“…Thanks to the high sensitivity of the chemical bonding and electronic structures to the carbon vacancies, the nonstoichiometric carbides usually exhibit significantly different properties from the stoichiometric ones . For the nonstoichiometric carbides, the ordering arrangement of carbon vacancies has been believed to favor the enhancement of hardness − and yield stress. , Similarly, their potential applications are subject to the influence of chemical stability at high temperature. To date, however, there has been no report on oxidation of the nonstoichiometric carbides with the ordered carbon vacancies, especially the role of ordered vacancies in oxidation.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Diffusion of Oxygen through Ordered Carbon Vacancies in Zr₂C_x: The Formation of Ordered Zr₂C_xO_y

Xiang

Liu

et al. 2012

Inorg. Chem.

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Investigations are performed on low-temperature oxygen diffusion in the carbon vacancy ordered ZrC(0.6)and thus induced formation of the oxygen atom ordered ZrC(0.6)O(0.4). Theoretically, a superstructure of Zr(2)CO can be constructed via the complete substitution of carbon vacancies with O atoms in the Zr(2)C model. In the ordered ZrC(0.6), the consecutive arrangement of vacancies forms the vacancy channels along some zone axes in the C sublattice. Through these vacancy channels, the thermally activated oxygen diffusion is significantly facilitated. The oxygen atoms diffuse directly into and occupy the vacancies, producing the ordered ZrC(0.6)O(0.4). Relative to the ordered ZrC(0.6), the Zr positions are finely tuned in the ordered ZrC(0.6)O(0.4) because of the ionic Zr-O bonds. Because of this fine adjustment of Zr positions and the presence of oxygen atoms, the superstructural reflections are always observable in a selected area electron diffraction (SAED) pattern, despite the invisibility of superstructural reflections in ZrC(0.6) along some special zone axes. Similar to the vacancies in ordered ZrC(0.6), the ordering arrangement of O atoms in the ordered ZrC(0.6)O(0.4) is in nanoscale length, thus forming the nano superstructural domains with irregular shapes.

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“…The oxide on the HfC 0.67 is also denser, with less porosity and cracking, than that of HfC 0.98 . It is noted that the properties of binary transition metal carbide (MC), including the hardness, 22,23 yield strength and steam corrosion resistance, 24,25 are sensitive to the carbon concentration. [26][27][28][29] In this study, (Zr,Ti)C x (x = 0.7-1.0) powders were fabricated by a modified spark plasma sintering (SPS) apparatus.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms responsible for enhancing low‐temperature oxidation resistance of nonstoichiometric (Zr,Ti)C

et al. 2022

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A series of (Zr,Ti)Cx (x = 0.7–1.0) samples were fabricated by a modified spark plasma sintering apparatus to investigate the effects of carbon concentration and Ti substitutions on the oxidation behavior. Crushed powders of (Zr,Ti)Cx were oxidized in lab air (N2–20‐vol.% O2) from room temperature to 900°C. The results indicated that Zr0.8Ti0.2C0.8, with a nominal carbon concentration x = 0.8, displayed good oxidation resistance, which was attributed to the formation of dense t‐(Zr,Ti)O2 oxide solid solution. During the oxidation of (Zr,Ti)Cx, Ti substitutions for Zr enhanced the outward diffusion of carbon, enabling a uniform carbon layer and a Zr–Ti–C–O layer on the surface of carbides. The formed carbon layer improved the oxidation resistance of (Zr,Ti)Cx below 550°C, where carbon is relatively oxidation resistant. Increasing the Ti concentration was found to enhance the oxidation resistance of (Zr,Ti)Cx with an increased oxidation onset temperature (672 ± 2°C for Zr0.8Ti0.2C0.8).

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Ordering effects on the microstructure and microhardness of nonstoichiometric titanium carbide TiCy

Cited by 12 publications

References 7 publications

Lattice rigidity in high‐entropy carbide ceramics with carbon vacancies

Lattice rigidity in high‐entropy carbide ceramics with carbon vacancies

Low-Temperature Diffusion of Oxygen through Ordered Carbon Vacancies in Zr₂C_x: The Formation of Ordered Zr₂C_xO_y

Mechanisms responsible for enhancing low‐temperature oxidation resistance of nonstoichiometric (Zr,Ti)C

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Ordering effects on the microstructure and microhardness of nonstoichiometric titanium carbide TiCy

Cited by 12 publications

References 7 publications

Lattice rigidity in high‐entropy carbide ceramics with carbon vacancies

Lattice rigidity in high‐entropy carbide ceramics with carbon vacancies

Low-Temperature Diffusion of Oxygen through Ordered Carbon Vacancies in Zr2Cx: The Formation of Ordered Zr2CxOy

Mechanisms responsible for enhancing low‐temperature oxidation resistance of nonstoichiometric (Zr,Ti)C

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Low-Temperature Diffusion of Oxygen through Ordered Carbon Vacancies in Zr₂C_x: The Formation of Ordered Zr₂C_xO_y