Fe–N phases

6 phases (tier A 3, tier C 1, liquid 1, gas 1); 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 · Fe–N system page · Markdown · field reference

Phases of the Fe–N system (6)
Phase	Structure	Basis	Stability (calculated)	TDB models
BCC_A2 phase:fe-n:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 6 of 6 calculated diagram(s): 300–2499.79 K, x(N) 0–0.00058	6
FCC_A1 phase:fe-n:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 6 of 6 calculated diagram(s): 1172.13–1680.35 K, x(N) 0–0.00134	6
FE4N_L1 phase:fe-n:fe4n-l1	Fe4N · L'1 · cP5 · Pm-3m (221)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	not stable in 6 calculated diagram(s)	6
HCP_A3 phase:fe-n:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 6 calculated diagram(s)	6
LIQUID phase:fe-n:liquid	liquid	liquid	stable in 6 of 6 calculated diagram(s): 1808.38–2500 K, x(N) 0–0.00216	6
N2GAS phase:fe-n:n2gas	gas	gas	stable in 6 of 6 calculated diagram(s): 300–2500 K, x(N) 1–1	6

BCC_A2 (Fe–N)

Id: phase:fe-n: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 6 of 6 calculated diagram(s): 300–2499.79 K, x(N) 0–0.00058
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:fe-n:bcc-a2
tdb: tdb:FeN-16Goe.tdb:BCC_A2, tdb:FeN-20Kou.tdb:BCC_A2, tdb:FeN-87Fri.tdb:BCC_A2, tdb:FeN-91Fri-LB.tdb:BCC_A2, tdb:FeN-93Du-mod.tdb:BCC_A2, tdb:FeN-93Du.tdb:BCC_A2

TDB models of BCC_A2 (6): PHASE and CONSTITUENT statements as written

FeN-16Goe.tdb: BCC_A2, type code %B, sha256 eddeea978f7c05e4…

39: PHASE BCC_A2 %B 2 1 3 !
40: CONST BCC_A2 : FE : N VA% : !

FeN-20Kou.tdb: BCC_A2, type code %B, sha256 37f1edb7a040f1d2…

37: PHASE BCC_A2 %B 2 1 3 !
38: CONST BCC_A2 : FE : N VA% : !

FeN-87Fri.tdb: BCC_A2, type code %B, sha256 b38a41b18e42bbef…

35: PHASE BCC_A2 %B 2 1 3 !
36: CONST BCC_A2 : FE : N VA% : !

FeN-91Fri-LB.tdb: BCC_A2, type code %B, sha256 dd61cb0ecd6570c0…

43: PHASE BCC_A2 %B 2 1 3 !
44: CONST BCC_A2 : FE : N VA% : !

FeN-93Du-mod.tdb: BCC_A2, type code %B, sha256 73a8d69e4021ea32…

41: PHASE BCC_A2 %B 2 1 3 !
42: CONST BCC_A2 : FE : N VA% : !

FeN-93Du.tdb: BCC_A2, type code %B, sha256 d651be243743cfad…

36: PHASE BCC_A2 %B 2 1 3 !
37: CONST BCC_A2 : FE : N VA% : !

Example references (4 of 4; assessments first):

doi:10.1007/BF02667880 H. Du, J. Phase Equilib., 14, 682-93(1993).
assessment that models this phase
doi:10.1016/0364-5916(87)90004-6 K. Frisk, Calphad, 11, 127-34(1987).
assessment that models this phase
doi:10.1016/0364-5916(91)90028-I K. Frisk, Calphad, 15, 79-106(1991).
assessment that models this phase
doi:10.1016/j.calphad.2020.102197 R. Kouba, K. Rayane, M. Keddam, Calphad, 71, 1ß2197(2020).
assessment that models this phase

FCC_A1 (Fe–N)

Id: phase:fe-n: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 6 of 6 calculated diagram(s): 1172.13–1680.35 K, x(N) 0–0.00134
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:fe-n:fcc-a1
tdb: tdb:FeN-16Goe.tdb:FCC_A1, tdb:FeN-20Kou.tdb:FCC_A1, tdb:FeN-87Fri.tdb:FCC_A1, tdb:FeN-91Fri-LB.tdb:FCC_A1, tdb:FeN-93Du-mod.tdb:FCC_A1, tdb:FeN-93Du.tdb:FCC_A1

TDB models of FCC_A1 (6): PHASE and CONSTITUENT statements as written

FeN-16Goe.tdb: FCC_A1, type code %A, sha256 eddeea978f7c05e4…

34: PHASE FCC_A1 %A 2 1 1 !
35: CONST FCC_A1 : FE : N VA% : !

FeN-20Kou.tdb: FCC_A1, type code %A, sha256 37f1edb7a040f1d2…

32: PHASE FCC_A1 %A 2 1 1 !
33: CONST FCC_A1 : FE : N VA% : !

FeN-87Fri.tdb: FCC_A1, type code %A, sha256 b38a41b18e42bbef…

30: PHASE FCC_A1 %A 2 1 1 !
31: CONST FCC_A1 : FE : N VA% : !

FeN-91Fri-LB.tdb: FCC_A1, type code %A, sha256 dd61cb0ecd6570c0…

38: PHASE FCC_A1 %A 2 1 1 !
39: CONST FCC_A1 : FE : N VA% : !

FeN-93Du-mod.tdb: FCC_A1, type code %A, sha256 73a8d69e4021ea32…

36: PHASE FCC_A1 %A 2 1 1 !
37: CONST FCC_A1 : FE : N VA% : !

FeN-93Du.tdb: FCC_A1, type code %A, sha256 d651be243743cfad…

31: PHASE FCC_A1 %A 2 1 1 !
32: CONST FCC_A1 : FE : N VA% : !

Example references (4 of 4; assessments first):

doi:10.1007/BF02667880 H. Du, J. Phase Equilib., 14, 682-93(1993).
assessment that models this phase
doi:10.1016/0364-5916(87)90004-6 K. Frisk, Calphad, 11, 127-34(1987).
assessment that models this phase
doi:10.1016/0364-5916(91)90028-I K. Frisk, Calphad, 15, 79-106(1991).
assessment that models this phase
doi:10.1016/j.calphad.2020.102197 R. Kouba, K. Rayane, M. Keddam, Calphad, 71, 1ß2197(2020).
assessment that models this phase

FE4N_L1 (Fe–N)

Id: phase:fe-n:fe4n-l1; status assigned
Structure: Fe4N · L'1 · cP5 · Pm-3m (221); type st:l-1-fe4n-cp5; 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 (name_has_descriptive_tokens:L1, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stability: not stable in 6 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:fe-n:fe4n-l1
tdb: tdb:FeN-16Goe.tdb:FE4N_L1, tdb:FeN-20Kou.tdb:FE4N_L1, tdb:FeN-87Fri.tdb:FE4N_L1, tdb:FeN-91Fri-LB.tdb:FE4N_L1, tdb:FeN-93Du-mod.tdb:FE4N_L1, tdb:FeN-93Du.tdb:FE4N_L1

TDB models of FE4N_L1 (6): PHASE and CONSTITUENT statements as written

FeN-16Goe.tdb: FE4N_L1, type code %, sha256 eddeea978f7c05e4…

49: PHASE FE4N_L1 % 2 4 1 !
50: CONST FE4N_L1 : FE : N VA :!

FeN-20Kou.tdb: FE4N_L1, type code %, sha256 37f1edb7a040f1d2…

47: PHASE FE4N_L1 % 2 4 1 !
48: CONST FE4N_L1 : FE : N VA :!

FeN-87Fri.tdb: FE4N_L1, type code %, sha256 b38a41b18e42bbef…

45: PHASE FE4N_L1 % 2 4 1 !
46: CONST FE4N_L1 : FE : N :!

FeN-91Fri-LB.tdb: FE4N_L1, type code %, sha256 dd61cb0ecd6570c0…

53: PHASE FE4N_L1 % 2 4 1 !
54: CONST FE4N_L1 : FE : N :!

FeN-93Du-mod.tdb: FE4N_L1, type code %, sha256 73a8d69e4021ea32…

51: PHASE FE4N_L1 % 2 4 1 !
52: CONST FE4N_L1 : FE : N VA :!

FeN-93Du.tdb: FE4N_L1, type code %, sha256 d651be243743cfad…

46: PHASE FE4N_L1 % 2 4 1 !
47: CONST FE4N_L1 : FE : N VA :!

Example references (4 of 4; assessments first):

doi:10.1007/BF02667880 H. Du, J. Phase Equilib., 14, 682-93(1993).
assessment that models this phase
doi:10.1016/0364-5916(87)90004-6 K. Frisk, Calphad, 11, 127-34(1987).
assessment that models this phase
doi:10.1016/0364-5916(91)90028-I K. Frisk, Calphad, 15, 79-106(1991).
assessment that models this phase
doi:10.1016/j.calphad.2020.102197 R. Kouba, K. Rayane, M. Keddam, Calphad, 71, 1ß2197(2020).
assessment that models this phase

HCP_A3 (Fe–N)

Id: phase:fe-n: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: not stable in 6 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:fe-n:hcp-a3
tdb: tdb:FeN-16Goe.tdb:HCP_A3, tdb:FeN-20Kou.tdb:HCP_A3, tdb:FeN-87Fri.tdb:HCP_A3, tdb:FeN-91Fri-LB.tdb:HCP_A3, tdb:FeN-93Du-mod.tdb:HCP_A3, tdb:FeN-93Du.tdb:HCP_A3

TDB models of HCP_A3 (6): PHASE and CONSTITUENT statements as written

FeN-16Goe.tdb: HCP_A3, type code %, sha256 eddeea978f7c05e4…

44: PHASE HCP_A3 % 2 1 0.5 !
45: CONST HCP_A3 : FE : N VA% : !

FeN-20Kou.tdb: HCP_A3, type code %, sha256 37f1edb7a040f1d2…

42: PHASE HCP_A3 % 2 1 0.5 !
43: CONST HCP_A3 : FE : N VA% : !

FeN-87Fri.tdb: HCP_A3, type code %, sha256 b38a41b18e42bbef…

40: PHASE HCP_A3 % 2 1 0.5 !
41: CONST HCP_A3 : FE : N VA% : !

FeN-91Fri-LB.tdb: HCP_A3, type code %, sha256 dd61cb0ecd6570c0…

48: PHASE HCP_A3 % 2 1 0.5 !
49: CONST HCP_A3 : FE : N VA% : !

FeN-93Du-mod.tdb: HCP_A3, type code %, sha256 73a8d69e4021ea32…

46: PHASE HCP_A3 % 2 1 0.5 !
47: CONST HCP_A3 : FE : N VA% : !

FeN-93Du.tdb: HCP_A3, type code %, sha256 d651be243743cfad…

41: PHASE HCP_A3 % 2 1 0.5 !
42: CONST HCP_A3 : FE : N VA% : !

Example references (4 of 4; assessments first):

doi:10.1007/BF02667880 H. Du, J. Phase Equilib., 14, 682-93(1993).
assessment that models this phase
doi:10.1016/0364-5916(87)90004-6 K. Frisk, Calphad, 11, 127-34(1987).
assessment that models this phase
doi:10.1016/0364-5916(91)90028-I K. Frisk, Calphad, 15, 79-106(1991).
assessment that models this phase
doi:10.1016/j.calphad.2020.102197 R. Kouba, K. Rayane, M. Keddam, Calphad, 71, 1ß2197(2020).
assessment that models this phase

LIQUID (Fe–N)

Id: phase:fe-n:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 6 of 6 calculated diagram(s): 1808.38–2500 K, x(N) 0–0.00216
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:fe-n:liquid
tdb: tdb:FeN-16Goe.tdb:LIQUID, tdb:FeN-20Kou.tdb:LIQUID, tdb:FeN-87Fri.tdb:LIQUID, tdb:FeN-91Fri-LB.tdb:LIQUID, tdb:FeN-93Du-mod.tdb:LIQUID, tdb:FeN-93Du.tdb:LIQUID

TDB models of LIQUID (6): PHASE and CONSTITUENT statements as written

FeN-16Goe.tdb: LIQUID, type code %, sha256 eddeea978f7c05e4…

29: PHASE LIQUID:L % 1 1 !
30: CONST LIQUID:L : FE N : !

FeN-20Kou.tdb: LIQUID, type code %, sha256 37f1edb7a040f1d2…

27: PHASE LIQUID:L % 1 1 !
28: CONST LIQUID:L : FE N : !

FeN-87Fri.tdb: LIQUID, type code %, sha256 b38a41b18e42bbef…

25: PHASE LIQUID:L % 1 1 !
26: CONST LIQUID:L : FE N : !

FeN-91Fri-LB.tdb: LIQUID, type code %, sha256 dd61cb0ecd6570c0…

33: PHASE LIQUID:L % 1 1 !
34: CONST LIQUID:L : FE N : !

FeN-93Du-mod.tdb: LIQUID, type code %, sha256 73a8d69e4021ea32…

31: PHASE LIQUID:L % 1 1 !
32: CONST LIQUID:L : FE N : !

FeN-93Du.tdb: LIQUID, type code %, sha256 d651be243743cfad…

26: PHASE LIQUID:L % 1 1 !
27: CONST LIQUID:L : FE N : !

Example references (4 of 4; assessments first):

doi:10.1007/BF02667880 H. Du, J. Phase Equilib., 14, 682-93(1993).
assessment that models this phase
doi:10.1016/0364-5916(87)90004-6 K. Frisk, Calphad, 11, 127-34(1987).
assessment that models this phase
doi:10.1016/0364-5916(91)90028-I K. Frisk, Calphad, 15, 79-106(1991).
assessment that models this phase
doi:10.1016/j.calphad.2020.102197 R. Kouba, K. Rayane, M. Keddam, Calphad, 71, 1ß2197(2020).
assessment that models this phase

N2GAS (Fe–N)

Id: phase:fe-n:n2gas; status assigned
Structure: gas; type st:gas; gas; confidence high
Stability: stable in 6 of 6 calculated diagram(s): 300–2500 K, x(N) 1–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (7): corpus: corpus:phase:fe-n:n2gas
tdb: tdb:FeN-16Goe.tdb:N2GAS, tdb:FeN-20Kou.tdb:N2GAS, tdb:FeN-87Fri.tdb:N2GAS, tdb:FeN-91Fri-LB.tdb:N2GAS, tdb:FeN-93Du-mod.tdb:N2GAS, tdb:FeN-93Du.tdb:N2GAS

TDB models of N2GAS (6): PHASE and CONSTITUENT statements as written

FeN-16Goe.tdb: N2GAS, type code %, sha256 eddeea978f7c05e4…

52: PHASE N2GAS % 1 1 !
53: CONST N2GAS : N2 : !

FeN-20Kou.tdb: N2GAS, type code %, sha256 37f1edb7a040f1d2…

50: PHASE N2GAS % 1 1 !
51: CONST N2GAS : N2 : !

FeN-87Fri.tdb: N2GAS, type code %, sha256 b38a41b18e42bbef…

48: PHASE N2GAS % 1 1 !
49: CONST N2GAS : N2 : !

FeN-91Fri-LB.tdb: N2GAS, type code %, sha256 dd61cb0ecd6570c0…

56: PHASE N2GAS % 1 1 !
57: CONST N2GAS : N2 : !

FeN-93Du-mod.tdb: N2GAS, type code %, sha256 73a8d69e4021ea32…

54: PHASE N2GAS % 1 1 !
55: CONST N2GAS : N2 : !

FeN-93Du.tdb: N2GAS, type code %, sha256 d651be243743cfad…

49: PHASE N2GAS % 1 1 !
50: CONST N2GAS : N2 : !

Example references (4 of 4; assessments first):

doi:10.1007/BF02667880 H. Du, J. Phase Equilib., 14, 682-93(1993).
assessment that models this phase
doi:10.1016/0364-5916(87)90004-6 K. Frisk, Calphad, 11, 127-34(1987).
assessment that models this phase
doi:10.1016/0364-5916(91)90028-I K. Frisk, Calphad, 15, 79-106(1991).
assessment that models this phase
doi:10.1016/j.calphad.2020.102197 R. Kouba, K. Rayane, M. Keddam, Calphad, 71, 1ß2197(2020).
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}
}