C–Nb system

56 accepted literature values from 2 paper(s) (experimental 30, model 13, DFT 13); 0 calculated phase diagram(s). 5 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: JSON · CSV · interactive explorer · phases (6) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	30
model	13
DFT	13

Accepted values by property group
Property group	Values
invariant reaction	25
phase transition	2
formation	3
heat capacity / entropy / enthalpy	16
crystal structure	10

Convex hulls: Materials Project DFT hull · OQMD DFT hull · CALPHAD hull NbC-01Lee · CALPHAD hull NbC-13Khv · CALPHAD hull NbC-90Hua · CALPHAD hull NbC-97Hua-LB

Invariant reactions (literature)

Invariant reactions reported in the literature for the C–Nb system (25)
T (K)	Reaction / phases	Compositions (mole fraction)	Class	Source	Location	Quote
3886	congruent melting: NbC = Liquid	NbC: C 0.45	model	[1] Huang 1990	Table 1, p. 3, row 18 report
3886	congruent melting: NbC = Liquid	NbC: C 0.44	experimental	[1] Huang 1990 cites RUDY 1968	Table 1, p. 3, row 17 report
3873	congruent melting: NbC = Liquid	NbC: C 0.5	experimental	[1] Huang 1990 cites KIMURA 1961	Table 1, p. 3, row 16 report
3773	congruent melting: NbC = Liquid	NbC: C 0.46	experimental	[1] Huang 1990 cites STORMS 1960	Table 1, p. 3, row 14 report
3753	congruent melting: NbC = Liquid	NbC: C 0.5, Nb 0.5; Liquid: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites NADLER 1960	Table 1, p. 3, row 15 report
3673	Liquid = NbC + graphite	NbC: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites STORMS 1960	Table 1, p. 3, row 19 report
3578	Liquid = NbC + graphite	Liquid: C 0.6; NbC: C 0.49	experimental	[1] Huang 1990 cites RUDY 1968	Table 1, p. 3, row 23 report
3573	Liquid = NbC + graphite	Liquid: C 0.6; NbC: C 0.49	model	[1] Huang 1990	Table 1, p. 3, row 24 report
3573	Liquid = NbC + graphite	Liquid: C 0.605; NbC: C 0.5	experimental	[1] Huang 1990 cites KIMURA 1961	Table 1, p. 3, row 21 report
3493	Liquid = NbC + graphite	NbC: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites NADLER 1960	Table 1, p. 3, row 20 report
3493	Liquid = NbC + graphite	NbC: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites ADELSBERG 1966	Table 1, p. 3, row 22 report
3363	Nb2C = Liquid + NbC	Nb2C: C 0.333; Liquid: C 0.32; NbC: C 0.36	experimental	[1] Huang 1990 cites STORMS 1960	Table 1, p. 3, row 7 report
3353	Nb2C = Liquid + NbC	Nb2C: C 0.333333, Nb 0.666667; NbC: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites NADLER 1960	Table 1, p. 3, row 8 report
3353	Nb2C = Liquid + NbC	Nb2C: C 0.333; Liquid: C 0.3; NbC: C 0.36	experimental	[1] Huang 1990 cites KIMURA 1961	Table 1, p. 3, row 9 report
3308	Nb2C = Liquid + NbC	Nb2C: C 0.345; Liquid: C 0.3; NbC: C 0.37	experimental	[1] Huang 1990 cites RUDY 1968	Table 1, p. 3, row 10 report
2800	Nb2C = Liquid + NbC	Nb2C: C 0.333333, Nb 0.666667; NbC: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites w 1972	Table 1, p. 3, row 12 report
2800	Nb2C = Liquid + NbC	Nb2C: C 0.333333, Nb 0.666667; NbC: C 0.5, Nb 0.5	experimental	[1] Huang 1990 cites STORMS 1990	Table 1, p. 3, row 11 report
2800	Nb2C = Liquid + NbC	Nb2C: C 0.29; Liquid: C 0.15; NbC: C 0.29	model	[1] Huang 1990	Table 1, p. 3, row 13 report
2799	metatectic/catatectic: L-NbC-Nb2C		model	[1] Huang 1990	p. 4 report	The calculated three phase equilibrium L-NbC-Nb2C at 2799 K is metatectic instead of the typical peritectic equilibrium, as reported in most experimental work.
2613	Liquid = bcc + Nb2C	Liquid: C 0.135; bcc: C 0.06; Nb2C: C 0.28	experimental	[1] Huang 1990 cites KIMURA 1961	Table 1, p. 3, row 3 report
2608	Liquid = bcc + Nb2C	Liquid: C 0.105; bcc: C 0.06; Nb2C: C 0.28	experimental	[1] Huang 1990 cites STORMS 1960	Table 1, p. 3, row 1 report
2608	Liquid = bcc + Nb2C	Liquid: C 0.105; bcc: C 0.075; Nb2C: C 0.28	experimental	[1] Huang 1990 cites RUDY 1968	Table 1, p. 3, row 5 report
2608	Liquid = bcc + Nb2C	Liquid: C 0.105; bcc: C 0.053; Nb2C: C 0.28	model	[1] Huang 1990	Table 1, p. 3, row 6 report
2601	Liquid = bcc + Nb2C	Nb2C: C 0.333333, Nb 0.666667	experimental	[1] Huang 1990 cites NADLER 1960	Table 1, p. 3, row 2 report
2503	Liquid = bcc + Nb2C	Liquid: C 0.105; bcc: C 0.06; Nb2C: C 0.31	experimental	[1] Huang 1990 cites ELLIOTT 1961	Table 1, p. 3, row 4 report

Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from dft_parity.json.

Enthalpies of formation, C–Nb system (3)
Phase	Value	Class	Source	Location
Nb3C	34.3728 kJ/mol-atom	DFT	[2] Khvan 2012	Table 1, p. 4, row 1 report
Nb5C2	-15.8511 kJ/mol-atom	DFT	[2] Khvan 2012	Table 1, p. 4, row 2 report
Nb7C3	15.1964 kJ/mol-atom	DFT	[2] Khvan 2012	Table 1, p. 4, row 3 report

Other properties

Phase transition (2)

Phase transition, C–Nb system
Property	Value	T (K)	Phases / composition	Class	Source	Location	Quote
Phase transition	2800 K	2800	Nb2C	experimental	[1] Huang 1990	p. 2 report	Nb2C decomposes close to 2800 K and NbC melts congruently at 3886 K.
Phase transition	3886 K	3886	congruent transformation	experimental	[1] Huang 1990	p. 2 report	Nb2C decomposes close to 2800 K and NbC melts congruently at 3886 K.

Heat capacity / entropy / enthalpy (16)

Heat capacity / entropy / enthalpy, C–Nb system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Entropy printed: °S298	21.36 J/mol (basis unstated)/K	298.15	Nb2C alloy: Nb 0.666667	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 7 report
Entropy printed: °S298	21.65 J/mol (basis unstated)/K	298.15	Nb2C alloy: Nb 0.666667	model	[1] Huang 1990	Table 3, p. 8, row 8 report
Entropy printed: °S298	20.44 J/mol (basis unstated)/K	298.15	NbC0.702 alloy: Nb 0.587544	model	[1] Huang 1990	Table 3, p. 8, row 6 report
Entropy printed: °S298	18.75 J/mol (basis unstated)/K	298.15	NbC0.702 alloy: Nb 0.587544	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 5 report
Entropy printed: °S298	19.83 J/mol (basis unstated)/K	298.15	NbC0.825 alloy: Nb 0.547945	model	[1] Huang 1990	Table 3, p. 8, row 4 report
Entropy printed: °S298	18.04 J/mol (basis unstated)/K	298.15	NbC0.825 alloy: Nb 0.547945	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 3 report
Entropy printed: °S298	17.52 J/mol (basis unstated)/K	298.15	NbC0.98 alloy: Nb 0.505051	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 1 report
Entropy printed: °S298	17.45 J/mol (basis unstated)/K	298.15	NbC0.98 alloy: Nb 0.505051	model	[1] Huang 1990	Table 3, p. 8, row 2 report
Heat capacity printed: °Cp,298	21.17 J/mol (basis unstated)/K	298.15	Nb2C alloy: Nb 0.666667	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 7 report
Heat capacity printed: °Cp,298	20.93 J/mol (basis unstated)/K	298.15	Nb2C alloy: Nb 0.666667	model	[1] Huang 1990	Table 3, p. 8, row 8 report
Heat capacity printed: °Cp,298	19.87 J/mol (basis unstated)/K	298.15	NbC0.702 alloy: Nb 0.587544	model	[1] Huang 1990	Table 3, p. 8, row 6 report
Heat capacity printed: °Cp,298	19.59 J/mol (basis unstated)/K	298.15	NbC0.702 alloy: Nb 0.587544	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 5 report
Heat capacity printed: °Cp,298	19.34 J/mol (basis unstated)/K	298.15	NbC0.825 alloy: Nb 0.547945	model	[1] Huang 1990	Table 3, p. 8, row 4 report
Heat capacity printed: °Cp,298	19.28 J/mol (basis unstated)/K	298.15	NbC0.825 alloy: Nb 0.547945	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 3 report
Heat capacity printed: °Cp,298	18.57 J/mol (basis unstated)/K	298.15	NbC0.98 alloy: Nb 0.505051	experimental	[1] Huang 1990 cites SANDENAW 1965	Table 3, p. 8, row 1 report
Heat capacity printed: °Cp,298	18.77 J/mol (basis unstated)/K	298.15	NbC0.98 alloy: Nb 0.505051	model	[1] Huang 1990	Table 3, p. 8, row 2 report

Crystal structure (10)

Crystal structure, C–Nb system
Property	Value	Phases / composition	Class	Source	Location
Lattice a printed: a	5.08 Å	Nb3C alloy: Nb 0.75	DFT	[2] Khvan 2012	Table 1, p. 4, row 1 report
Lattice a printed: a	12.66 Å	Nb5C2 alloy: Nb 0.714286	DFT	[2] Khvan 2012	Table 1, p. 4, row 2 report
Lattice a printed: a	4.53 Å	Nb7C3 alloy: Nb 0.7	DFT	[2] Khvan 2012	Table 1, p. 4, row 3 report
Lattice b printed: b	7.66 Å	Nb3C alloy: Nb 0.75	DFT	[2] Khvan 2012	Table 1, p. 4, row 1 report
Lattice b printed: b	5.45 Å	Nb5C2 alloy: Nb 0.714286	DFT	[2] Khvan 2012	Table 1, p. 4, row 2 report
Lattice b printed: b	7.92 Å	Nb7C3 alloy: Nb 0.7	DFT	[2] Khvan 2012	Table 1, p. 4, row 3 report
Lattice c printed: c	6.31 Å	Nb3C alloy: Nb 0.75	DFT	[2] Khvan 2012	Table 1, p. 4, row 1 report
Lattice c printed: c	5.87 Å	Nb5C2 alloy: Nb 0.714286	DFT	[2] Khvan 2012	Table 1, p. 4, row 2 report
Lattice c printed: c	15.97 Å	Nb7C3 alloy: Nb 0.7	DFT	[2] Khvan 2012	Table 1, p. 4, row 3 report
lattice unspecified axis printed: β	97.23 unknown	Nb5C2 alloy: Nb 0.714286	DFT	[2] Khvan 2012	Table 1, p. 4, row 2 report

Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990). doi:10.1179/mst.1990.6.8.687
A.V. Khvan, B. Hallstedt, K. Chang, Thermodynamic assessment of Cr–Nb–C and Mn–Nb–C systems, Calphad 39, 54-61 (2012). doi:10.1016/j.calphad.2012.09.002

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735569
R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). doi:10.5281/zenodo.23735891
R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file. Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

@misc{orchid_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}