C–Hf 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–Hf system page · Markdown · field reference

Phases of the C–Hf system (6)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
DIAMOND_A4 phase:c-hf:a4-diamond	C (diamond) · A4 · cF8 · Fd-3m (227)	tier A: standard phase name	not stable in 2 calculated diagram(s)	0	2
GRAPHITE_A9 phase:c-hf:a9-graphite	C (graphite) · A9 · hP4 · P6_3/mmc (194)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–4000 K, x(C) 1–1	0	2
BCC_A2 phase:c-hf:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 2016.13–2506.99 K, x(C) 0–0.01068	6	2
FCC_A1 phase:c-hf:fcc-a1	NaCl · B1 · cF8 · Fm-3m (225)	assigned	stable in 2 of 2 calculated diagram(s): 300–4000 K, x(C) 0.33419–0.49872	14	2
HCP_A3 phase:c-hf:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 2 of 2 calculated diagram(s): 300–2649.08 K, x(C) 0–0.13983	8	2
LIQUID phase:c-hf:liquid	liquid	liquid	stable in 2 of 2 calculated diagram(s): 2463.94–4000 K, x(C) 0–0.74728	15	2

DIAMOND_A4 (C–Hf)

Id: phase:c-hf: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 2 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:c-hf:a4-diamond
tdb: tdb:HfC-16Pan.tdb:DIAMOND_A4, tdb:HfC-97Bit-LB.tdb:DIAMOND_A4

TDB models of DIAMOND_A4 (2): PHASE and CONSTITUENT statements as written

HfC-16Pan.tdb: DIAMOND_A4, type code %, sha256 6a221c5bb6daa283…

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

HfC-97Bit-LB.tdb: DIAMOND_A4, type code %, sha256 920403c39afc1e2c…

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

Example references (2 of 2; assessments first):

doi:10.1007/s11669-997-0061-3 H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the binary system hafnium-carbon (Hf-C), JPE 18, 344-356 (1997).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.001 Y. Pan, P. Zhou, Y. Peng, Y. Du, F. Luo, Calphad, 53, 1-9(2016).
assessment that models this phase

GRAPHITE_A9 (C–Hf)

Id: phase:c-hf: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 2 of 2 calculated diagram(s): 300–4000 K, x(C) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:c-hf:a9-graphite
tdb: tdb:HfC-16Pan.tdb:GRAPHITE_A9, tdb:HfC-97Bit-LB.tdb:GRAPHITE_A9

TDB models of GRAPHITE_A9 (2): PHASE and CONSTITUENT statements as written

HfC-16Pan.tdb: GRAPHITE_A9, type code %, sha256 6a221c5bb6daa283…

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

HfC-97Bit-LB.tdb: GRAPHITE_A9, type code %, sha256 920403c39afc1e2c…

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

Example references (2 of 2; assessments first):

doi:10.1007/s11669-997-0061-3 H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the binary system hafnium-carbon (Hf-C), JPE 18, 344-356 (1997).
assessment that models this phase
doi:10.1016/j.calphad.2016.02.001 Y. Pan, P. Zhou, Y. Peng, Y. Du, F. Luo, Calphad, 53, 1-9(2016).
assessment that models this phase

BCC_A2 (C–Hf)

Id: phase:c-hf: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 2 of 2 calculated diagram(s): 2016.13–2506.99 K, x(C) 0–0.01068
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:c-hf:bcc-a2
paper: paper:10.1007/s11669-997-0061-3:βHf
tdb: tdb:HfC-16Pan.tdb:BCC_A2, tdb:HfC-97Bit-LB.tdb:BCC_A2

TDB models of BCC_A2 (2): PHASE and CONSTITUENT statements as written

HfC-16Pan.tdb: BCC_A2, type code %B, sha256 6a221c5bb6daa283…

31: PHASE BCC_A2 %B 2 1 3 !
32: CONST BCC_A2 : HF : C VA% : !

HfC-97Bit-LB.tdb: BCC_A2, type code %B, sha256 920403c39afc1e2c…

30: PHASE BCC_A2 %B 2 1 3 !
31: CONST BCC_A2 : HF : C VA% : !

Example references (3 of 3; assessments first):

doi:10.1007/s11669-997-0061-3 H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the binary system hafnium-carbon (Hf-C), JPE 18, 344-356 (1997).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2016.02.001 Y. Pan, P. Zhou, Y. Peng, Y. Du, F. Luo, Calphad, 53, 1-9(2016).
assessment that models this phase
doi:10.1016/0364-5916(91)90030-n A.T. Dinsdale, SGTE data for pure elements, Calphad 15, 317-425 (1991).
cited as the source of values for this phase

FCC_A1 (C–Hf)

Id: phase:c-hf: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 2 of 2 calculated diagram(s): 300–4000 K, x(C) 0.33419–0.49872
Literature: 14 values (14 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:c-hf:fcc-a1
paper: paper:10.1007/s11669-997-0061-3:HfC, paper:10.1007/s11669-997-0061-3:HfC1-x
tdb: tdb:HfC-16Pan.tdb:FCC_A1, tdb:HfC-97Bit-LB.tdb:FCC_A1

TDB models of FCC_A1 (2): PHASE and CONSTITUENT statements as written

HfC-16Pan.tdb: FCC_A1, type code %A, sha256 6a221c5bb6daa283…

26: PHASE FCC_A1 %A 2 1 1 !
27: CONST FCC_A1 : HF : C% VA : !

HfC-97Bit-LB.tdb: FCC_A1, type code %A, sha256 920403c39afc1e2c…

25: PHASE FCC_A1 %A 2 1 1 !
26: CONST FCC_A1 : HF : C% VA : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-997-0061-3 H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the binary system hafnium-carbon (Hf-C), JPE 18, 344-356 (1997).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2016.02.001 Y. Pan, P. Zhou, Y. Peng, Y. Du, F. Luo, Calphad, 53, 1-9(2016).
assessment that models this phase

HCP_A3 (C–Hf)

Id: phase:c-hf: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 2 of 2 calculated diagram(s): 300–2649.08 K, x(C) 0–0.13983
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:c-hf:hcp-a3
paper: paper:10.1007/s11669-997-0061-3:(αHf), paper:10.1007/s11669-997-0061-3:αHf
tdb: tdb:HfC-16Pan.tdb:HCP_A3, tdb:HfC-97Bit-LB.tdb:HCP_A3

TDB models of HCP_A3 (2): PHASE and CONSTITUENT statements as written

HfC-16Pan.tdb: HCP_A3, type code %A, sha256 6a221c5bb6daa283…

36: PHASE HCP_A3 %A 2 1 0.5 !
37: CONST HCP_A3 : HF : C VA% : !

HfC-97Bit-LB.tdb: HCP_A3, type code %A, sha256 920403c39afc1e2c…

35: PHASE HCP_A3 %A 2 1 0.5 !
36: CONST HCP_A3 : HF : C VA% : !

Example references (2 of 2; assessments first):

doi:10.1007/s11669-997-0061-3 H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the binary system hafnium-carbon (Hf-C), JPE 18, 344-356 (1997).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2016.02.001 Y. Pan, P. Zhou, Y. Peng, Y. Du, F. Luo, Calphad, 53, 1-9(2016).
assessment that models this phase

LIQUID (C–Hf)

Id: phase:c-hf:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 2 of 2 calculated diagram(s): 2463.94–4000 K, x(C) 0–0.74728
Literature: 15 values (15 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:c-hf:liquid
paper: paper:10.1007/s11669-997-0061-3:L
tdb: tdb:HfC-16Pan.tdb:LIQUID, tdb:HfC-97Bit-LB.tdb:LIQUID

TDB models of LIQUID (2): PHASE and CONSTITUENT statements as written

HfC-16Pan.tdb: LIQUID, type code %, sha256 6a221c5bb6daa283…

21: PHASE LIQUID:L % 1 1 !
22: CONST LIQUID:L : C HF : !

HfC-97Bit-LB.tdb: LIQUID, type code %, sha256 920403c39afc1e2c…

20: PHASE LIQUID:L % 1 1 !
21: CONST LIQUID:L : C HF : !

Example references (3 of 3; assessments first):

doi:10.1007/s11669-997-0061-3 H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the binary system hafnium-carbon (Hf-C), JPE 18, 344-356 (1997).
assessment that models this phase; reports values for this phase
doi:10.1016/j.calphad.2016.02.001 Y. Pan, P. Zhou, Y. Peng, Y. Du, F. Luo, Calphad, 53, 1-9(2016).
assessment that models this phase
doi:10.1016/0364-5916(91)90030-n A.T. Dinsdale, SGTE data for pure elements, Calphad 15, 317-425 (1991).
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}
}