Fe–Hf phases

8 phases (tier A 6, tier C 1, liquid 1); 8 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 · Fe–Hf system page · Markdown · field reference

Phases of the Fe–Hf system (8)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:fe-hf:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–3999.8 K, x(Hf) 0–1	0	1
FCC_A1 phase:fe-hf:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1159.9–1722.59 K, x(Hf) 0–0.00018	0	1
FE2HF_C14 phase:fe-hf:fe2hf-c14	MgZn2 · C14 · hP12 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2091.22 K, x(Hf) 0.24299–0.31962	0	1
FE2HF_C15 phase:fe-hf:fe2hf-c15	Cu2Mg · C15 · cF24 · Fd-3m (227)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1474.54 K, x(Hf) 0.33333–0.33333	0	1
FE2HF_C36 phase:fe-hf:fe2hf-c36	MgNi2 · C36 · hP24 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1474.54–1933.37 K, x(Hf) 0.33333–0.33333	0	1
FEHF2 phase:fe-hf:fehf2	NiTi2 · cF96 · Fd-3m (227)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1531.26 K, x(Hf) 0.66667–0.66667	8	1
HCP_A3 phase:fe-hf:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2503.56 K, x(Hf) 1–1	0	1
LIQUID phase:fe-hf:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1573.55–4000 K, x(Hf) 0–1	0	1

BCC_A2 (Fe–Hf)

Id: phase:fe-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 1 of 1 calculated diagram(s): 300–3999.8 K, x(Hf) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:bcc-a2
tdb: tdb:FeHf-08Idb.tdb:BCC_A2

TDB models of BCC_A2 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: BCC_A2, type code %B, sha256 2a85ddea9bbae84b…

40: PHASE BCC_A2 %B 2 1 3 !
41: CONST BCC_A2 : FE% HF% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase

FCC_A1 (Fe–Hf)

Id: phase:fe-hf:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1159.9–1722.59 K, x(Hf) 0–0.00018
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:fcc-a1
tdb: tdb:FeHf-08Idb.tdb:FCC_A1

TDB models of FCC_A1 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: FCC_A1, type code %A, sha256 2a85ddea9bbae84b…

35: PHASE FCC_A1 %A 2 1 1 !
36: CONST FCC_A1 : FE% HF : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase

FE2HF_C14 (Fe–Hf)

Id: phase:fe-hf:fe2hf-c14; status assigned
Structure: MgZn2 · C14 · hP12 · P6_3/mmc (194); type st:c14-mgzn2-hp12; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–2091.22 K, x(Hf) 0.24299–0.31962
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:fe2hf-c14
tdb: tdb:FeHf-08Idb.tdb:FE2HF_C14

TDB models of FE2HF_C14 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: FE2HF_C14, type code %, sha256 2a85ddea9bbae84b…

50: PHASE FE2HF_C14 % 2 2 1 !
51: CONST FE2HF_C14 : FE : FE HF% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase

FE2HF_C15 (Fe–Hf)

Id: phase:fe-hf:fe2hf-c15; status assigned
Structure: Cu2Mg · C15 · cF24 · Fd-3m (227); type st:c15-cu2mg-cf24; tier A: standard phase name; confidence high
Stoichiometry: Fe 0.6667, Hf 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1474.54 K, x(Hf) 0.33333–0.33333
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:fe2hf-c15
tdb: tdb:FeHf-08Idb.tdb:FE2HF_C15

TDB models of FE2HF_C15 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: FE2HF_C15, type code %, sha256 2a85ddea9bbae84b…

55: PHASE FE2HF_C15 % 2 2 1 !
56: CONST FE2HF_C15 : FE : HF : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase

FE2HF_C36 (Fe–Hf)

Id: phase:fe-hf:fe2hf-c36; status assigned
Structure: MgNi2 · C36 · hP24 · P6_3/mmc (194); type st:c36-mgni2-hp24; tier A: standard phase name; confidence high
Stoichiometry: Fe 0.6667, Hf 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 1474.54–1933.37 K, x(Hf) 0.33333–0.33333
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:fe2hf-c36
tdb: tdb:FeHf-08Idb.tdb:FE2HF_C36

TDB models of FE2HF_C36 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: FE2HF_C36, type code %, sha256 2a85ddea9bbae84b…

60: PHASE FE2HF_C36 % 2 2 1 !
61: CONST FE2HF_C36 : FE : HF : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase

FEHF2 (Fe–Hf)

Id: phase:fe-hf:fehf2; status assigned
Structure: NiTi2 · cF96 · Fd-3m (227); type st:niti2-cf96; tier C: assessor-stated (Hallstedt 2025 crystallographic table); confidence assessor-stated
Structure source: B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, supplementary crystallographic table (mmc2) doi:10.1016/j.calphad.2025.102833
Caveat: not certain from the name or DFT alone (no_on_hull_entry_in_oqmd, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Fe 0.3333, Hf 0.6667
Stability: stable in 1 of 1 calculated diagram(s): 300–1531.26 K, x(Hf) 0.66667–0.66667
Literature: 8 values (8 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:fe-hf:fehf2
paper: paper:10.1016/j.jallcom.2007.02.036:FeHF2, paper:10.1016/j.jallcom.2007.02.036:FeHf2
tdb: tdb:FeHf-08Idb.tdb:FEHF2

TDB models of FEHF2 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: FEHF2, type code %, sha256 2a85ddea9bbae84b…

65: PHASE FEHF2 % 2 1 2 !
66: CONST FEHF2 : FE : HF : !

Example references (4 of 4; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase; reports values for this phase
doi:10.1007/bf02665763 J. C. Gachon, N. Selhaoui, B. Aba, J. Hertz, Comparison between measured and predicted enthalpies of formation, JPE 13, 506-511 (1992).
cited as the source of values for this phase
doi:10.1016/0364-5916(83)90030-5 A.K. Niessen, F.R. de Boer, R. Boom, P.F. de Chatel, W.C.M. Mattens, A.R. Miedema, CALPHAD 7 (1983) 51–70.
cited as the source of values for this phase
doi:10.1016/0364-5916(85)90032-x C. Colinet, A. Pasturel, P. Hicter, Calphad 9 (1985) 71–99.
cited as the source of values for this phase

HCP_A3 (Fe–Hf)

Id: phase:fe-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 1 of 1 calculated diagram(s): 300–2503.56 K, x(Hf) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:hcp-a3
tdb: tdb:FeHf-08Idb.tdb:HCP_A3

TDB models of HCP_A3 (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: HCP_A3, type code %A, sha256 2a85ddea9bbae84b…

45: PHASE HCP_A3 %A 2 1 0.5 !
46: CONST HCP_A3 : FE HF% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
assessment that models this phase

LIQUID (Fe–Hf)

Id: phase:fe-hf:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1573.55–4000 K, x(Hf) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:fe-hf:liquid
tdb: tdb:FeHf-08Idb.tdb:LIQUID

TDB models of LIQUID (1): PHASE and CONSTITUENT statements as written

FeHf-08Idb.tdb: LIQUID, type code %, sha256 2a85ddea9bbae84b…

30: PHASE LIQUID:L % 1 1 !
31: CONST LIQUID:L : FE HF : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2007.02.036 M. Idbenali, N. Selhaoui, L. Bouirden, C. Servant, Thermodynamic assessment of the Fe–Hf binary system, Journal of Alloys and Compounds 456, 151-158 (2008).
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}
}