C–Nb phases

6 phases (tier A 4, liquid 1, interstitial_fcc_a1_compound 1); 5 stable in a calculated diagram. Structure types are assigned only when the stored evidence supports an assignment under the stated tier rules (tier A: standard phase name; tier B: unique Materials Project + OQMD on-hull match, DFT-supported; tier C: one structure stated by the assessment's crystallographic table, assessor-stated); other phases list candidates and are marked needs_review. Stability is from phase diagrams calculated with pycalphad from the SGTE binary collection (evidence class: model).

Data: interactive registry · full JSON · C–Nb system page · Markdown · field reference

Phases of the C–Nb system (6)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
DIAMOND_A4 phase:c-nb:a4-diamond	C (diamond) · A4 · cF8 · Fd-3m (227)	tier A: standard phase name	not stable in 5 calculated diagram(s)	0	5
GRAPHITE_A9 phase:c-nb:a9-graphite	C (graphite) · A9 · hP4 · P6_3/mmc (194)	tier A: standard phase name	stable in 5 of 5 calculated diagram(s): 300–4000 K, x(C) 1–1	0	5
BCC_A2 phase:c-nb:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 5 of 5 calculated diagram(s): 300–4000 K, x(C) 0–0.05461	6	5
FCC_A1 phase:c-nb:fcc-a1	NaCl · B1 · cF8 · Fm-3m (225)	assigned	stable in 5 of 5 calculated diagram(s): 300–3923.28 K, x(C) 0.29181–0.5	18	5
HCP_A3 phase:c-nb:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 5 of 5 calculated diagram(s): 300–3282.3 K, x(C) 0.28816–0.33333	13	5
LIQUID phase:c-nb:liquid	liquid	liquid	stable in 5 of 5 calculated diagram(s): 2597.4–4000 K, x(C) 0–0.71742	24	5

DIAMOND_A4 (C–Nb)

Id: phase:c-nb:a4-diamond; status assigned
Structure: C (diamond) · A4 · cF8 · Fd-3m (227); type st:a4-c-diamond-cf8; tier A: standard phase name; confidence high
Stoichiometry: C 1.0000
Stability: not stable in 5 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (6): corpus: corpus:phase:c-nb:a4-diamond
tdb: tdb:NbC-01Lee.tdb:DIAMOND_A4, tdb:NbC-13Khv.tdb:DIAMOND_A4, tdb:NbC-16Pen.tdb:DIAMOND_A4, tdb:NbC-90Hua.tdb:DIAMOND_A4, tdb:NbC-97Hua-LB.tdb:DIAMOND_A4

TDB models of DIAMOND_A4 (5): PHASE and CONSTITUENT statements as written

NbC-01Lee.tdb: DIAMOND_A4, type code %, sha256 9f0b0d890e5bd1f1…

45: PHASE DIAMOND_A4 % 1 1 !
46: CONST DIAMOND_A4 : C : !

NbC-13Khv.tdb: DIAMOND_A4, type code %, sha256 4ae1654829e38036…

47: PHASE DIAMOND_A4 % 1 1 !
48: CONST DIAMOND_A4 : C : !

NbC-16Pen.tdb: DIAMOND_A4, type code %, sha256 22d77b32d5bd2a4f…

39: PHASE DIAMOND_A4 % 1 1 !
40: CONST DIAMOND_A4 : C : !

NbC-90Hua.tdb: DIAMOND_A4, type code %, sha256 3b357fde12f03aea…

45: PHASE DIAMOND_A4 % 1 1 !
46: CONST DIAMOND_A4 : C : !

NbC-97Hua-LB.tdb: DIAMOND_A4, type code %, sha256 81f536c9df24e381…

45: PHASE DIAMOND_A4 % 1 1 !
46: CONST DIAMOND_A4 : C : !

Example references (5 of 5; assessments first):

doi:10.1007/s11661-001-0033-x Byeong-Joo Lee, Thermodynamic assessment of the Fe-Nb-Ti-C-N system, Metall Mater Trans A 32, 2423-2439 (2001).
assessment that models this phase
doi:10.1016/j.calphad.2012.11.001 A.V. Khvan, B. Hallstedt, Calphad, 40, 10-15(2013), based on B.-J. Lee, Metall. Mater. Trans. A, 32A, 2423-39(2001).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.004 Y. Peng, P. Zhou, M. Bu, W. Zhang, Y. Du, Calphad, 53, 10-19(2016).
assessment that models this phase
doi:10.1179/mst.1990.6.8.687 Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990).
assessment that models this phase
doi:10.3139/ijmr-1997-0010 W. Huang, M. Selleby, Z. Metallkd., 88, 55-62(1997).
assessment that models this phase

GRAPHITE_A9 (C–Nb)

Id: phase:c-nb:a9-graphite; status assigned
Structure: C (graphite) · A9 · hP4 · P6_3/mmc (194); type st:a9-c-graphite-hp4; tier A: standard phase name; confidence high
Stoichiometry: C 1.0000
Stability: stable in 5 of 5 calculated diagram(s): 300–4000 K, x(C) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:c-nb:a9-graphite, corpus:phase:c-nb:graphite-a9
tdb: tdb:NbC-01Lee.tdb:GRAPHITE_A9, tdb:NbC-13Khv.tdb:GRAPHITE_A9, tdb:NbC-16Pen.tdb:GRAPHITE_A9, tdb:NbC-90Hua.tdb:GRAPHITE_A9, tdb:NbC-97Hua-LB.tdb:GRAPHITE_A9

TDB models of GRAPHITE_A9 (5): PHASE and CONSTITUENT statements as written

NbC-01Lee.tdb: GRAPHITE_A9, type code %, sha256 9f0b0d890e5bd1f1…

50: PHASE GRAPHITE_A9 % 1 1 !
51: CONST GRAPHITE_A9 : C : !

NbC-13Khv.tdb: GRAPHITE_A9, type code %, sha256 4ae1654829e38036…

52: PHASE GRAPHITE_A9 % 1 1 !
53: CONST GRAPHITE_A9 : C : !

NbC-16Pen.tdb: GRAPHITE_A9, type code %, sha256 22d77b32d5bd2a4f…

44: PHASE GRAPHITE_A9 % 1 1 !
45: CONST GRAPHITE_A9 : C : !

NbC-90Hua.tdb: GRAPHITE_A9, type code %, sha256 3b357fde12f03aea…

50: PHASE GRAPHITE_A9 % 1 1 !
51: CONST GRAPHITE_A9 : C : !

NbC-97Hua-LB.tdb: GRAPHITE_A9, type code %, sha256 81f536c9df24e381…

50: PHASE GRAPHITE_A9 % 1 1 !
51: CONST GRAPHITE_A9 : C : !

Example references (5 of 5; assessments first):

doi:10.1007/s11661-001-0033-x Byeong-Joo Lee, Thermodynamic assessment of the Fe-Nb-Ti-C-N system, Metall Mater Trans A 32, 2423-2439 (2001).
assessment that models this phase
doi:10.1016/j.calphad.2012.11.001 A.V. Khvan, B. Hallstedt, Calphad, 40, 10-15(2013), based on B.-J. Lee, Metall. Mater. Trans. A, 32A, 2423-39(2001).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.004 Y. Peng, P. Zhou, M. Bu, W. Zhang, Y. Du, Calphad, 53, 10-19(2016).
assessment that models this phase
doi:10.1179/mst.1990.6.8.687 Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990).
assessment that models this phase
doi:10.3139/ijmr-1997-0010 W. Huang, M. Selleby, Z. Metallkd., 88, 55-62(1997).
assessment that models this phase

BCC_A2 (C–Nb)

Id: phase:c-nb:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; tier A: standard phase name; confidence high
Stability: stable in 5 of 5 calculated diagram(s): 300–4000 K, x(C) 0–0.05461
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:c-nb:bcc-a2
paper: paper:10.1179/mst.1990.6.8.687:bcc
tdb: tdb:NbC-01Lee.tdb:BCC_A2, tdb:NbC-13Khv.tdb:BCC_A2, tdb:NbC-16Pen.tdb:BCC_A2, tdb:NbC-90Hua.tdb:BCC_A2, tdb:NbC-97Hua-LB.tdb:BCC_A2

TDB models of BCC_A2 (5): PHASE and CONSTITUENT statements as written

NbC-01Lee.tdb: BCC_A2, type code %B, sha256 9f0b0d890e5bd1f1…

35: PHASE BCC_A2 %B 2 1 3 !
36: CONST BCC_A2 : NB% : C VA% : !

NbC-13Khv.tdb: BCC_A2, type code %B, sha256 4ae1654829e38036…

37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : NB% : C VA% : !

NbC-16Pen.tdb: BCC_A2, type code %B, sha256 22d77b32d5bd2a4f…

29: PHASE BCC_A2 %B 2 1 3 !
30: CONST BCC_A2 : NB% : C VA% : !

NbC-90Hua.tdb: BCC_A2, type code %B, sha256 3b357fde12f03aea…

35: PHASE BCC_A2 %B 2 1 3 !
36: CONST BCC_A2 : NB% : C VA% : !

NbC-97Hua-LB.tdb: BCC_A2, type code %B, sha256 81f536c9df24e381…

35: PHASE BCC_A2 %B 2 1 3 !
36: CONST BCC_A2 : NB% : C VA% : !

Example references (5 of 5; assessments first):

doi:10.1179/mst.1990.6.8.687 Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990).
assessment that models this phase; reports values for this phase
doi:10.1007/s11661-001-0033-x Byeong-Joo Lee, Thermodynamic assessment of the Fe-Nb-Ti-C-N system, Metall Mater Trans A 32, 2423-2439 (2001).
assessment that models this phase
doi:10.1016/j.calphad.2012.11.001 A.V. Khvan, B. Hallstedt, Calphad, 40, 10-15(2013), based on B.-J. Lee, Metall. Mater. Trans. A, 32A, 2423-39(2001).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.004 Y. Peng, P. Zhou, M. Bu, W. Zhang, Y. Du, Calphad, 53, 10-19(2016).
assessment that models this phase
doi:10.3139/ijmr-1997-0010 W. Huang, M. Selleby, Z. Metallkd., 88, 55-62(1997).
assessment that models this phase

FCC_A1 (C–Nb)

Id: phase:c-nb:fcc-a1; status assigned
Structure: NaCl · B1 · cF8 · Fm-3m (225); type st:b1-nacl-cf8; interstitial_fcc_a1_compound; confidence high
Stability: stable in 5 of 5 calculated diagram(s): 300–3923.28 K, x(C) 0.29181–0.5
Literature: 18 values (18 accepted) from 1 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:c-nb:fcc-a1
paper: paper:10.1179/mst.1990.6.8.687:NbC
tdb: tdb:NbC-01Lee.tdb:FCC_A1, tdb:NbC-13Khv.tdb:FCC_A1, tdb:NbC-16Pen.tdb:FCC_A1, tdb:NbC-90Hua.tdb:FCC_A1, tdb:NbC-97Hua-LB.tdb:FCC_A1

TDB models of FCC_A1 (5): PHASE and CONSTITUENT statements as written

NbC-01Lee.tdb: FCC_A1, type code %A, sha256 9f0b0d890e5bd1f1…

30: PHASE FCC_A1 %A 2 1 1 !
31: CONST FCC_A1 : NB : C VA% : !

NbC-13Khv.tdb: FCC_A1, type code %A, sha256 4ae1654829e38036…

32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : NB : C VA% : !

NbC-16Pen.tdb: FCC_A1, type code %A, sha256 22d77b32d5bd2a4f…

24: PHASE FCC_A1 %A 2 1 1 !
25: CONST FCC_A1 : NB : C VA% : !

NbC-90Hua.tdb: FCC_A1, type code %A, sha256 3b357fde12f03aea…

30: PHASE FCC_A1 %A 2 1 1 !
31: CONST FCC_A1 : NB : C VA% : !

NbC-97Hua-LB.tdb: FCC_A1, type code %A, sha256 81f536c9df24e381…

30: PHASE FCC_A1 %A 2 1 1 !
31: CONST FCC_A1 : NB : C VA% : !

Example references (5 of 5; assessments first):

doi:10.1179/mst.1990.6.8.687 Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990).
assessment that models this phase; reports values for this phase
doi:10.1007/s11661-001-0033-x Byeong-Joo Lee, Thermodynamic assessment of the Fe-Nb-Ti-C-N system, Metall Mater Trans A 32, 2423-2439 (2001).
assessment that models this phase
doi:10.1016/j.calphad.2012.11.001 A.V. Khvan, B. Hallstedt, Calphad, 40, 10-15(2013), based on B.-J. Lee, Metall. Mater. Trans. A, 32A, 2423-39(2001).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.004 Y. Peng, P. Zhou, M. Bu, W. Zhang, Y. Du, Calphad, 53, 10-19(2016).
assessment that models this phase
doi:10.3139/ijmr-1997-0010 W. Huang, M. Selleby, Z. Metallkd., 88, 55-62(1997).
assessment that models this phase

HCP_A3 (C–Nb)

Id: phase:c-nb:hcp-a3; status assigned
Structure: Mg · A3 · hP2 · P6_3/mmc (194); type st:a3-mg-hp2; tier A: standard phase name; confidence high
Stability: stable in 5 of 5 calculated diagram(s): 300–3282.3 K, x(C) 0.28816–0.33333
Literature: 13 values (13 accepted) from 1 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:c-nb:hcp-a3
paper: paper:10.1179/mst.1990.6.8.687:Nb2C
tdb: tdb:NbC-01Lee.tdb:HCP_A3, tdb:NbC-13Khv.tdb:HCP_A3, tdb:NbC-16Pen.tdb:HCP_A3, tdb:NbC-90Hua.tdb:HCP_A3, tdb:NbC-97Hua-LB.tdb:HCP_A3

TDB models of HCP_A3 (5): PHASE and CONSTITUENT statements as written

NbC-01Lee.tdb: HCP_A3, type code %A, sha256 9f0b0d890e5bd1f1…

40: PHASE HCP_A3 %A 2 1 0.5 !
41: CONST HCP_A3 : NB : C VA% : !

NbC-13Khv.tdb: HCP_A3, type code %A, sha256 4ae1654829e38036…

42: PHASE HCP_A3 %A 2 1 0.5 !
43: CONST HCP_A3 : NB : C VA% : !

NbC-16Pen.tdb: HCP_A3, type code %A, sha256 22d77b32d5bd2a4f…

34: PHASE HCP_A3 %A 2 1 0.5 !
35: CONST HCP_A3 : NB : C VA% : !

NbC-90Hua.tdb: HCP_A3, type code %A, sha256 3b357fde12f03aea…

40: PHASE HCP_A3 %A 2 1 0.5 !
41: CONST HCP_A3 : NB : C VA% : !

NbC-97Hua-LB.tdb: HCP_A3, type code %A, sha256 81f536c9df24e381…

40: PHASE HCP_A3 %A 2 1 0.5 !
41: CONST HCP_A3 : NB : C VA% : !

Example references (5 of 5; assessments first):

doi:10.1179/mst.1990.6.8.687 Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990).
assessment that models this phase; reports values for this phase
doi:10.1007/s11661-001-0033-x Byeong-Joo Lee, Thermodynamic assessment of the Fe-Nb-Ti-C-N system, Metall Mater Trans A 32, 2423-2439 (2001).
assessment that models this phase
doi:10.1016/j.calphad.2012.11.001 A.V. Khvan, B. Hallstedt, Calphad, 40, 10-15(2013), based on B.-J. Lee, Metall. Mater. Trans. A, 32A, 2423-39(2001).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.004 Y. Peng, P. Zhou, M. Bu, W. Zhang, Y. Du, Calphad, 53, 10-19(2016).
assessment that models this phase
doi:10.3139/ijmr-1997-0010 W. Huang, M. Selleby, Z. Metallkd., 88, 55-62(1997).
assessment that models this phase

LIQUID (C–Nb)

Id: phase:c-nb:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 5 of 5 calculated diagram(s): 2597.4–4000 K, x(C) 0–0.71742
Literature: 24 values (24 accepted) from 1 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:c-nb:liquid
paper: paper:10.1179/mst.1990.6.8.687:Liquid
tdb: tdb:NbC-01Lee.tdb:LIQUID, tdb:NbC-13Khv.tdb:LIQUID, tdb:NbC-16Pen.tdb:LIQUID, tdb:NbC-90Hua.tdb:LIQUID, tdb:NbC-97Hua-LB.tdb:LIQUID

TDB models of LIQUID (5): PHASE and CONSTITUENT statements as written

NbC-01Lee.tdb: LIQUID, type code %, sha256 9f0b0d890e5bd1f1…

25: PHASE LIQUID:L % 1 1 !
26: CONST LIQUID:L : C NB : !

NbC-13Khv.tdb: LIQUID, type code %, sha256 4ae1654829e38036…

27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : C NB : !

NbC-16Pen.tdb: LIQUID, type code %, sha256 22d77b32d5bd2a4f…

19: PHASE LIQUID:L % 1 1 !
20: CONST LIQUID:L : C NB : !

NbC-90Hua.tdb: LIQUID, type code %, sha256 3b357fde12f03aea…

25: PHASE LIQUID:L % 1 1 !
26: CONST LIQUID:L : C NB : !

NbC-97Hua-LB.tdb: LIQUID, type code %, sha256 81f536c9df24e381…

25: PHASE LIQUID:L % 1 1 !
26: CONST LIQUID:L : C NB : !

Example references (5 of 5; assessments first):

doi:10.1179/mst.1990.6.8.687 Weiming Huang, Thermodynamic evaluation of Nb–C system, Materials Science and Technology 6, 687-694 (1990).
assessment that models this phase; reports values for this phase
doi:10.1007/s11661-001-0033-x Byeong-Joo Lee, Thermodynamic assessment of the Fe-Nb-Ti-C-N system, Metall Mater Trans A 32, 2423-2439 (2001).
assessment that models this phase
doi:10.1016/j.calphad.2012.11.001 A.V. Khvan, B. Hallstedt, Calphad, 40, 10-15(2013), based on B.-J. Lee, Metall. Mater. Trans. A, 32A, 2423-39(2001).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.004 Y. Peng, P. Zhou, M. Bu, W. Zhang, Y. Du, Calphad, 53, 10-19(2016).
assessment that models this phase
doi:10.3139/ijmr-1997-0010 W. Huang, M. Selleby, Z. Metallkd., 88, 55-62(1997).
assessment that models this phase

Please cite

R. Arróyave, J. Saal, D. Shin, ORCHID-Registry: phase registry of binary systems (version 2026.10; Version 1, machine-extracted), Zenodo (2026). doi:10.5281/zenodo.23735970
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 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; 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); the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work). 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_phase_registry_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Registry: phase registry of binary systems}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735970},
  url       = {https://doi.org/10.5281/zenodo.23735970},
  note      = {Version 1, machine-extracted}
}

@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}
}