B–C phases

5 phases (tier A 2, liquid 1, needs_review 2); 4 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 · B–C system page · Markdown · field reference

Phases of the B–C system (5)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
DIAMOND_A4 phase:b-c: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:b-c: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) 0.97686–1	3	5
BETA_RHOMBO_B phase:b-c:b-beta-rhombo		needs_review	stable in 5 of 5 calculated diagram(s): 300–2408.12 K, x(C) 0–0.01428	3	5
B4C_D1G phase:b-c:b4c-d1g		needs_review	stable in 5 of 5 calculated diagram(s): 300–2742.41 K, x(C) 0.05–0.2	9	5
LIQUID phase:b-c:liquid	liquid	liquid	stable in 5 of 5 calculated diagram(s): 2346.16–4000 K, x(C) 0–0.61157	9	5

DIAMOND_A4 (B–C)

Id: phase:b-c: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:b-c:a4-diamond
tdb: tdb:BC-12Sae.tdb:DIAMOND_A4, tdb:BC-14Rog.tdb:DIAMOND_A4, tdb:BC-24Eno.tdb:DIAMOND_A4, tdb:BC-94Kas.tdb:DIAMOND_A4, tdb:BC-98Kas-LB.tdb:DIAMOND_A4

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

BC-12Sae.tdb: DIAMOND_A4, type code %, sha256 290e26418cf735dd…

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

BC-14Rog.tdb: DIAMOND_A4, type code %, sha256 61f54c7a828b16dd…

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

BC-24Eno.tdb: DIAMOND_A4, type code %, sha256 2105df9640f51822…

41: PHASE DIAMOND_A4 % 1 1 !
42: CONST DIAMOND_A4 : C : !

BC-94Kas.tdb: DIAMOND_A4, type code %, sha256 178cb3073b3b2693…

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

BC-98Kas-LB.tdb: DIAMOND_A4, type code %, sha256 953024537b05421e…

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

Example references (3 of 3; assessments first):

doi:10.1007/s11669-024-01162-3 Masanori Enoki, Kota Takahashi, Hiroshi Ohtani, Thermodynamic Analysis of the Fe-B-C Ternary System and an Evaluation of the Grain Boundary Segregation Behavior of B and C, J. Phase Equilib. Diffus. 45, 1244-1259 (2024).
assessment that models this phase
doi:10.1016/j.actamat.2012.09.029 Arkapol Saengdeejing, James E. Saal, Venkateswara Rao Manga, Zi-Kui Liu, Defects in boron carbide: First-principles calculations and CALPHAD modeling, Acta Materialia 60, 7207-7215 (2012).
assessment that models this phase
doi:10.1016/j.calphad.2013.07.016 Peter F. Rogl, Jan Vřešťál, Takaho Tanaka, Satoshi Takenouchi, The B-rich side of the B–C phase diagram, Calphad 44, 3-9 (2014).
assessment that models this phase

GRAPHITE_A9 (B–C)

Id: phase:b-c: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
Stability: stable in 5 of 5 calculated diagram(s): 300–4000 K, x(C) 0.97686–1
Literature: 3 values (3 accepted) from 2 papers
Interactive: phase registry entry

Names (9): corpus: corpus:phase:b-c:a9-graphite, corpus:phase:b-c:graphite-a9
paper: paper:10.1016/j.actamat.2012.09.029:Graphite, paper:sha256-85fd53a1a176b694:graphite
tdb: tdb:BC-12Sae.tdb:GRAPHITE_A9, tdb:BC-14Rog.tdb:GRAPHITE_A9, tdb:BC-24Eno.tdb:GRAPHITE_A9, tdb:BC-94Kas.tdb:GRAPHITE_A9, tdb:BC-98Kas-LB.tdb:GRAPHITE_A9

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

BC-12Sae.tdb: GRAPHITE_A9, type code %, sha256 290e26418cf735dd…

45: PHASE GRAPHITE_A9 % 1 1 !
46: CONST GRAPHITE_A9 : B C% : !

BC-14Rog.tdb: GRAPHITE_A9, type code %, sha256 61f54c7a828b16dd…

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

BC-24Eno.tdb: GRAPHITE_A9, type code %, sha256 2105df9640f51822…

46: PHASE GRAPHITE_A9 % 1 1 !
47: CONST GRAPHITE_A9 : B C% : !

BC-94Kas.tdb: GRAPHITE_A9, type code %, sha256 178cb3073b3b2693…

45: PHASE GRAPHITE_A9 % 1 1 !
46: CONST GRAPHITE_A9 : B C% : !

BC-98Kas-LB.tdb: GRAPHITE_A9, type code %, sha256 953024537b05421e…

43: PHASE GRAPHITE_A9 % 1 1 !
44: CONST GRAPHITE_A9 : B C% : !

Example references (3 of 3; assessments first):

doi:10.1016/j.actamat.2012.09.029 Arkapol Saengdeejing, James E. Saal, Venkateswara Rao Manga, Zi-Kui Liu, Defects in boron carbide: First-principles calculations and CALPHAD modeling, Acta Materialia 60, 7207-7215 (2012).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-024-01162-3 Masanori Enoki, Kota Takahashi, Hiroshi Ohtani, Thermodynamic Analysis of the Fe-B-C Ternary System and an Evaluation of the Grain Boundary Segregation Behavior of B and C, J. Phase Equilib. Diffus. 45, 1244-1259 (2024).
assessment that models this phase
doi:10.1016/j.calphad.2013.07.016 Peter F. Rogl, Jan Vřešťál, Takaho Tanaka, Satoshi Takenouchi, The B-rich side of the B–C phase diagram, Calphad 44, 3-9 (2014).
assessment that models this phase

BETA_RHOMBO_B (B–C)

Id: phase:b-c:b-beta-rhombo; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:RHOMBO; no_structure_token
Candidate (sgte_mmc2): beta-B · hR105 · R-3m (166) — Hallstedt 2025 mmc2 row for BETA_RHOMBO_B: beta-B
Candidate (tdb_comment): beta-B · hR105 · R-3m — BC-12Sae.tdb: 'Prototype beta-B (hR105, R-3m)'
Candidate (tdb_comment): beta-B · hR105 · R-3m — BC-14Rog.tdb: 'Prototype beta-B (hR105, R-3m)'
Candidate (tdb_comment): beta-B · hR105 · R-3m — BC-24Eno.tdb: 'Prototype beta-B (hR105, R-3m)'
Candidate (tdb_comment): beta-B · hR105 · R-3m — BC-94Kas.tdb: 'Prototype beta-B (hR105, R-3m)'
Candidate (tdb_comment): beta-B · hR105 · R-3m — BC-98Kas-LB.tdb: 'Prototype beta-B (hR105, R-3m)'
Stability: stable in 5 of 5 calculated diagram(s): 300–2408.12 K, x(C) 0–0.01428
Literature: 3 values (3 accepted) from 2 papers
Interactive: phase registry entry

Names (9): corpus: corpus:phase:b-c:b-beta-rhombo, corpus:phase:b-c:beta-rhombo-b
paper: paper:10.1016/j.actamat.2012.09.029:β-boron, paper:sha256-85fd53a1a176b694:β-rhombo-B
tdb: tdb:BC-12Sae.tdb:BETA_RHOMBO_B, tdb:BC-14Rog.tdb:BETA_RHOMBO_B, tdb:BC-24Eno.tdb:BETA_RHOMBO_B, tdb:BC-94Kas.tdb:BETA_RHOMBO_B, tdb:BC-98Kas-LB.tdb:BETA_RHOMBO_B

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

BC-12Sae.tdb: BETA_RHOMBO_B, type code %, sha256 290e26418cf735dd…

35: PHASE BETA_RHOMBO_B % 2 101 4 !
36: CONST BETA_RHOMBO_B : B : B C : !

BC-14Rog.tdb: BETA_RHOMBO_B, type code %, sha256 61f54c7a828b16dd…

34: PHASE BETA_RHOMBO_B % 2 93 12 !
35: CONST BETA_RHOMBO_B : B : B C : !

BC-24Eno.tdb: BETA_RHOMBO_B, type code %, sha256 2105df9640f51822…

36: PHASE BETA_RHOMBO_B % 2 101 4 !
37: CONST BETA_RHOMBO_B : B : B C : !

BC-94Kas.tdb: BETA_RHOMBO_B, type code %, sha256 178cb3073b3b2693…

35: PHASE BETA_RHOMBO_B % 1 1 !
36: CONST BETA_RHOMBO_B : B : !

BC-98Kas-LB.tdb: BETA_RHOMBO_B, type code %, sha256 953024537b05421e…

33: PHASE BETA_RHOMBO_B % 2 93 12 !
34: CONST BETA_RHOMBO_B : B : B C : !

Example references (3 of 3; assessments first):

doi:10.1016/j.actamat.2012.09.029 Arkapol Saengdeejing, James E. Saal, Venkateswara Rao Manga, Zi-Kui Liu, Defects in boron carbide: First-principles calculations and CALPHAD modeling, Acta Materialia 60, 7207-7215 (2012).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-024-01162-3 Masanori Enoki, Kota Takahashi, Hiroshi Ohtani, Thermodynamic Analysis of the Fe-B-C Ternary System and an Evaluation of the Grain Boundary Segregation Behavior of B and C, J. Phase Equilib. Diffus. 45, 1244-1259 (2024).
assessment that models this phase
doi:10.1016/j.calphad.2013.07.016 Peter F. Rogl, Jan Vřešťál, Takaho Tanaka, Satoshi Takenouchi, The B-rich side of the B–C phase diagram, Calphad 44, 3-9 (2014).
assessment that models this phase

B4C_D1G (B–C)

Id: phase:b-c:b4c-d1g; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:site_ratios_contradict_D1_g; site_ratios_contradict_D1_g:BC-14Rog.tdb; site_ratios_contradict_D1_g:BC-94Kas.tdb; site_ratios_contradict_D1_g:BC-98Kas-LB.tdb
Candidate (dft_mp): R-3m (166) — on-hull MP B13C2 at x(C)=0.1333
Candidate (dft_mp): Cm (8) — on-hull MP B4C at x(C)=0.2000
Candidate (dft_oqmd): R-3m (166) — on-hull OQMD B13 C2 at x(C)=0.1333
Candidate (dft_oqmd): Cm (8) — on-hull OQMD B4 C1 at x(C)=0.2000
Candidate (literature_printed): B13C2 · hR15 — printed with a label mapped to this phase
Candidate (name_token): B13C2 · D1_g · hR15 · R-3m (166) — Strukturbericht/word 'D1G' in the TDB name
Candidate (sgte_mmc2): B13C2 · D1_g · hR15 · R-3m (166) — Hallstedt 2025 mmc2 row for B4C_D1G: B4C
Candidate (tdb_comment): B13C2 · hR15 · R-3m — BC-12Sae.tdb: 'Prototype B13C2 (hR15, R-3m)'
Stability: stable in 5 of 5 calculated diagram(s): 300–2742.41 K, x(C) 0.05–0.2
Literature: 9 values (9 accepted) from 2 papers
Interactive: phase registry entry

Names (8): corpus: corpus:phase:b-c:b4c-d1g
paper: paper:10.1016/j.actamat.2012.09.029:B4+xC, paper:sha256-85fd53a1a176b694:B4C
tdb: tdb:BC-12Sae.tdb:B4C_D1G, tdb:BC-14Rog.tdb:B4C_D1G, tdb:BC-24Eno.tdb:B4C_D1G, tdb:BC-94Kas.tdb:B4C_D1G, tdb:BC-98Kas-LB.tdb:B4C_D1G

TDB models of B4C_D1G (5): PHASE and CONSTITUENT statements as written

BC-12Sae.tdb: B4C_D1G, type code %, sha256 290e26418cf735dd…

50: PHASE B4C_D1G % 5 11 1 1 1 1 !
51: CONST B4C_D1G : B : B C : B C VA : B VA : B C VA : !

BC-14Rog.tdb: B4C_D1G, type code %, sha256 61f54c7a828b16dd…

49: PHASE B4C_D1G % 2 1 1 !
50: CONST B4C_D1G : B12 B11C : B2 B2C BC2 : !

BC-24Eno.tdb: B4C_D1G, type code %, sha256 2105df9640f51822…

51: PHASE B4C_D1G % 5 11 1 1 1 1 !
52: CONST B4C_D1G : B : B C : B C VA : B VA : B C VA : !

BC-94Kas.tdb: B4C_D1G, type code %, sha256 178cb3073b3b2693…

50: PHASE B4C_D1G % 2 1 1 !
51: CONST B4C_D1G : B12 B11C : B2 B2C BC2 : !

BC-98Kas-LB.tdb: B4C_D1G, type code %, sha256 953024537b05421e…

48: PHASE B4C_D1G % 2 1 1 !
49: CONST B4C_D1G : B12 B11C : B2 B2C BC2 : !

Example references (4 of 4; assessments first):

doi:10.1016/j.actamat.2012.09.029 Arkapol Saengdeejing, James E. Saal, Venkateswara Rao Manga, Zi-Kui Liu, Defects in boron carbide: First-principles calculations and CALPHAD modeling, Acta Materialia 60, 7207-7215 (2012).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-024-01162-3 Masanori Enoki, Kota Takahashi, Hiroshi Ohtani, Thermodynamic Analysis of the Fe-B-C Ternary System and an Evaluation of the Grain Boundary Segregation Behavior of B and C, J. Phase Equilib. Diffus. 45, 1244-1259 (2024).
assessment that models this phase
doi:10.1016/j.calphad.2013.07.016 Peter F. Rogl, Jan Vřešťál, Takaho Tanaka, Satoshi Takenouchi, The B-rich side of the B–C phase diagram, Calphad 44, 3-9 (2014).
assessment that models this phase
doi:10.1016/0022-5088(83)90067-x M. Beauvy, Stoichiometric limits of carbon-rich boron carbide phases, Journal of the Less Common Metals 90, 169-175 (1983).
cited as the source of values for this phase

LIQUID (B–C)

Id: phase:b-c:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 5 of 5 calculated diagram(s): 2346.16–4000 K, x(C) 0–0.61157
Literature: 9 values (9 accepted) from 2 papers
Interactive: phase registry entry

Names (8): corpus: corpus:phase:b-c:liquid
paper: paper:10.1016/j.actamat.2012.09.029:Liquid, paper:sha256-85fd53a1a176b694:Liquid
tdb: tdb:BC-12Sae.tdb:LIQUID, tdb:BC-14Rog.tdb:LIQUID, tdb:BC-24Eno.tdb:LIQUID, tdb:BC-94Kas.tdb:LIQUID, tdb:BC-98Kas-LB.tdb:LIQUID

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

BC-12Sae.tdb: LIQUID, type code %, sha256 290e26418cf735dd…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : B C : !

BC-14Rog.tdb: LIQUID, type code %, sha256 61f54c7a828b16dd…

29: PHASE LIQUID:L % 1 1 !
30: CONST LIQUID:L : B C : !

BC-24Eno.tdb: LIQUID, type code %, sha256 2105df9640f51822…

31: PHASE LIQUID:L % 1 1 !
32: CONST LIQUID:L : B C : !

BC-94Kas.tdb: LIQUID, type code %, sha256 178cb3073b3b2693…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : B C : !

BC-98Kas-LB.tdb: LIQUID, type code %, sha256 953024537b05421e…

28: PHASE LIQUID:L % 1 1 !
29: CONST LIQUID:L : B C : !

Example references (4 of 4; assessments first):

doi:10.1016/j.actamat.2012.09.029 Arkapol Saengdeejing, James E. Saal, Venkateswara Rao Manga, Zi-Kui Liu, Defects in boron carbide: First-principles calculations and CALPHAD modeling, Acta Materialia 60, 7207-7215 (2012).
assessment that models this phase; reports values for this phase
doi:10.1007/s11669-024-01162-3 Masanori Enoki, Kota Takahashi, Hiroshi Ohtani, Thermodynamic Analysis of the Fe-B-C Ternary System and an Evaluation of the Grain Boundary Segregation Behavior of B and C, J. Phase Equilib. Diffus. 45, 1244-1259 (2024).
assessment that models this phase
doi:10.1016/j.calphad.2013.07.016 Peter F. Rogl, Jan Vřešťál, Takaho Tanaka, Satoshi Takenouchi, The B-rich side of the B–C phase diagram, Calphad 44, 3-9 (2014).
assessment that models this phase
doi:10.1016/0022-5088(83)90067-x M. Beauvy, Stoichiometric limits of carbon-rich boron carbide phases, Journal of the Less Common Metals 90, 169-175 (1983).
cited as the source of values for 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}
}