Ni–U phases

13 phases (tier A 7, tier C 2, liquid 1, needs_review 3); 12 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 · Ni–U system page · Markdown · field reference

Phases of the Ni–U system (13)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
ORTHORHOMBIC_A20 phase:ni-u:a20-orthorhombic	alpha-U · A20 · oC4 · Cmcm (63)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1047.02 K, x(U) 0.99994–1	0	1
BCC_A2 phase:ni-u:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1032.92–1407.99 K, x(U) 0.97548–1	4	1
FCC_A1 phase:ni-u:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1749.24 K, x(U) 0–0.01259	2	1
HCP_A3 phase:ni-u:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
LIQUID phase:ni-u:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1015.07–4000 K, x(U) 0–1	18	1
NI2U_C14 phase:ni-u:ni2u-c14	MgZn2 · C14 · hP12 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1259.2 K, x(U) 0.33333–0.33333	4	1
NI3U phase:ni-u:ni3u		needs_review	stable in 1 of 1 calculated diagram(s): 300–1536.06 K, x(U) 0.23–0.23	2	1
NI5U_C15B phase:ni-u:ni5u-c15b	AuBe5 · C15_b · cF24 · F-43m (216)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1583.48 K, x(U) 0.16667–0.16667	5	1
NI7U2_D2D phase:ni-u:ni7u2-d2d		needs_review	stable in 1 of 1 calculated diagram(s): 300–1570.32 K, x(U) 0.22–0.22	0	1
NI7U5 phase:ni-u:ni7u5	Ni7U5 · hR54 · R-3 (148)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1093.01 K, x(U) 0.41667–0.41667	4	1
NI9U7 phase:ni-u:ni9u7	Ni9U7 · mC46 · C2/m (12)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1055.94 K, x(U) 0.4375–0.4375	4	1
NIU6_D2C phase:ni-u:niu6-d2c	MnU6 · D2_c · tI28 · I4/mcm (140)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1063.55 K, x(U) 0.85714–0.85714	6	1
TETRAGONAL_U phase:ni-u:u-tetragonal		needs_review	stable in 1 of 1 calculated diagram(s): 935–1047.02 K, x(U) 0.98983–1	2	1

ORTHORHOMBIC_A20 (Ni–U)

Id: phase:ni-u:a20-orthorhombic; status assigned
Structure: alpha-U · A20 · oC4 · Cmcm (63); type st:a20-alpha-u-oc4; tier A: standard phase name; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 300–1047.02 K, x(U) 0.99994–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ni-u:a20-orthorhombic
tdb: tdb:NiU-09Wan.tdb:ORTHORHOMBIC_A20

TDB models of ORTHORHOMBIC_A20 (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: ORTHORHOMBIC_A20, type code %, sha256 9f6aef6a1ab79ad3…

43: PHASE ORTHORHOMBIC_A20 % 1 1 !
44: CONST ORTHORHOMBIC_A20 : NI U% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase

BCC_A2 (Ni–U)

Id: phase:ni-u: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): 1032.92–1407.99 K, x(U) 0.97548–1
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:bcc-a2
paper: paper:10.1016/j.jallcom.2009.07.168:γU
tdb: tdb:NiU-09Wan.tdb:BCC_A2

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

NiU-09Wan.tdb: BCC_A2, type code %B, sha256 9f6aef6a1ab79ad3…

33: PHASE BCC_A2 %B 2 1 3 !
34: CONST BCC_A2 : NI U% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

FCC_A1 (Ni–U)

Id: phase:ni-u: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): 300–1749.24 K, x(U) 0–0.01259
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:fcc-a1
paper: paper:10.1016/j.jallcom.2009.07.168:(Ni)
tdb: tdb:NiU-09Wan.tdb:FCC_A1

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

NiU-09Wan.tdb: FCC_A1, type code %A, sha256 9f6aef6a1ab79ad3…

28: PHASE FCC_A1 %A 2 1 1 !
29: CONST FCC_A1 : NI% U : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

HCP_A3 (Ni–U)

Id: phase:ni-u: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 1 calculated diagram(s)
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ni-u:hcp-a3
tdb: tdb:NiU-09Wan.tdb:HCP_A3

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

NiU-09Wan.tdb: HCP_A3, type code %A, sha256 9f6aef6a1ab79ad3…

38: PHASE HCP_A3 %A 2 1 0.5 !
39: CONST HCP_A3 : NI U : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase

LIQUID (Ni–U)

Id: phase:ni-u:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1015.07–4000 K, x(U) 0–1
Literature: 18 values (18 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:liquid
paper: paper:10.1016/j.jallcom.2009.07.168:L
tdb: tdb:NiU-09Wan.tdb:LIQUID

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

NiU-09Wan.tdb: LIQUID, type code %, sha256 9f6aef6a1ab79ad3…

23: PHASE LIQUID:L % 1 1 !
24: CONST LIQUID:L : NI U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

NI2U_C14 (Ni–U)

Id: phase:ni-u:ni2u-c14; status assigned
Structure: MgZn2 · C14 · hP12 · P6_3/mmc (194); type st:c14-mgzn2-hp12; tier A: standard phase name; confidence high
Stoichiometry: Ni 0.6667, U 0.3333
Stability: stable in 1 of 1 calculated diagram(s): 300–1259.2 K, x(U) 0.33333–0.33333
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:ni2u-c14
paper: paper:10.1016/j.jallcom.2009.07.168:UNi2
tdb: tdb:NiU-09Wan.tdb:NI2U_C14

TDB models of NI2U_C14 (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NI2U_C14, type code %, sha256 9f6aef6a1ab79ad3…

68: PHASE NI2U_C14 % 2 2 1 !
69: CONST NI2U_C14 : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

NI3U (Ni–U)

Id: phase:ni-u:ni3u; status needs_review
No structure assigned. Why: no_on_hull_entry_in_both; no_structure_token; sgte_mmc2_row_incomplete
Candidate (literature_printed): (Ni3U) · ? — printed with a label mapped to this phase
Candidate (sgte_mmc2): (Ni3U) — Hallstedt 2025 mmc2 row for NI3U: Ni3U
Stoichiometry: Ni 0.7700, U 0.2300
Stability: stable in 1 of 1 calculated diagram(s): 300–1536.06 K, x(U) 0.23–0.23
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:ni3u
paper: paper:10.1016/j.jallcom.2009.07.168:δ
tdb: tdb:NiU-09Wan.tdb:NI3U

TDB models of NI3U (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NI3U, type code %, sha256 9f6aef6a1ab79ad3…

63: PHASE NI3U % 2 0.77 0.23 !
64: CONST NI3U : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

NI5U_C15B (Ni–U)

Id: phase:ni-u:ni5u-c15b; status assigned
Structure: AuBe5 · C15_b · cF24 · F-43m (216); type st:c15-b-aube5-cf24; tier A: standard phase name; confidence high
Caveat: DFT agrees: on-hull mp-aaaaaefe and oqmd-17847, space group 216
Stoichiometry: Ni 0.8333, U 0.1667
Stability: stable in 1 of 1 calculated diagram(s): 300–1583.48 K, x(U) 0.16667–0.16667
Literature: 5 values (5 accepted) from 1 papers
Interactive: phase registry entry

Names (5): corpus: corpus:phase:ni-u:ni5u-c15b
mp: mp:mp-aaaaaefe
oqmd: oqmd:oqmd-17847
paper: paper:10.1016/j.jallcom.2009.07.168:UNi5
tdb: tdb:NiU-09Wan.tdb:NI5U_C15B

TDB models of NI5U_C15B (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NI5U_C15B, type code %, sha256 9f6aef6a1ab79ad3…

53: PHASE NI5U_C15B % 2 5 1 !
54: CONST NI5U_C15B : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

NI7U2_D2D (Ni–U)

Id: phase:ni-u:ni7u2-d2d; status needs_review
No structure assigned. Why: assessment_declared_blocked_by:stoichiometry_contradicts_D2_d; stoichiometry_contradicts_D2_d:NiU-09Wan.tdb
Candidate (name_token): CaCu5 · D2_d · hP6 · P6/mmm (191) — Strukturbericht/word 'D2D' in the TDB name
Candidate (sgte_mmc2): CaCu5 · D2_d · hP6 · P6/mmm (191) — Hallstedt 2025 mmc2 row for NI7U2_D2D: Ni7U2
Candidate (tdb_comment): CaCu5 · hP6 · P6/mmm — NiU-09Wan.tdb: 'Prototype CaCu5 (hP6, P6/mmm), epsilon'
Stoichiometry: Ni 0.7800, U 0.2200
Stability: stable in 1 of 1 calculated diagram(s): 300–1570.32 K, x(U) 0.22–0.22
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:ni-u:ni7u2-d2d
tdb: tdb:NiU-09Wan.tdb:NI7U2_D2D

TDB models of NI7U2_D2D (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NI7U2_D2D, type code %, sha256 9f6aef6a1ab79ad3…

58: PHASE NI7U2_D2D % 2 0.78 0.22 !
59: CONST NI7U2_D2D : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase

NI7U5 (Ni–U)

Id: phase:ni-u:ni7u5; status assigned
Structure: Ni7U5 · hR54 · R-3 (148); type st:ni7u5-hr54; 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_both, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Ni 0.5833, U 0.4167
Stability: stable in 1 of 1 calculated diagram(s): 300–1093.01 K, x(U) 0.41667–0.41667
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:ni7u5
paper: paper:10.1016/j.jallcom.2009.07.168:U5Ni7
tdb: tdb:NiU-09Wan.tdb:NI7U5

TDB models of NI7U5 (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NI7U5, type code %, sha256 9f6aef6a1ab79ad3…

73: PHASE NI7U5 % 2 7 5 !
74: CONST NI7U5 : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

NI9U7 (Ni–U)

Id: phase:ni-u:ni9u7; status assigned
Structure: Ni9U7 · mC46 · C2/m (12); type st:ni9u7-mc46; 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_both, no_structure_token); structure as stated in the SGTE crystallographic table for this phase name and system
Stoichiometry: Ni 0.5625, U 0.4375
Stability: stable in 1 of 1 calculated diagram(s): 300–1055.94 K, x(U) 0.4375–0.4375
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:ni9u7
paper: paper:10.1016/j.jallcom.2009.07.168:U7Ni9
tdb: tdb:NiU-09Wan.tdb:NI9U7

TDB models of NI9U7 (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NI9U7, type code %, sha256 9f6aef6a1ab79ad3…

78: PHASE NI9U7 % 2 9 7 !
79: CONST NI9U7 : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

NIU6_D2C (Ni–U)

Id: phase:ni-u:niu6-d2c; status assigned
Structure: MnU6 · D2_c · tI28 · I4/mcm (140); type st:d2-c-mnu6-ti28; tier A: standard phase name; confidence high
Stoichiometry: Ni 0.1429, U 0.8571
Stability: stable in 1 of 1 calculated diagram(s): 300–1063.55 K, x(U) 0.85714–0.85714
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:ni-u:niu6-d2c
paper: paper:10.1016/j.jallcom.2009.07.168:U6Ni
tdb: tdb:NiU-09Wan.tdb:NIU6_D2C

TDB models of NIU6_D2C (1): PHASE and CONSTITUENT statements as written

NiU-09Wan.tdb: NIU6_D2C, type code %, sha256 9f6aef6a1ab79ad3…

83: PHASE NIU6_D2C % 2 1 6 !
84: CONST NIU6_D2C : NI : U : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports values for this phase

TETRAGONAL_U (Ni–U)

Id: phase:ni-u:u-tetragonal; status needs_review
No structure assigned. Why: name_has_descriptive_tokens:TETRAGONAL; no_structure_token
Candidate (sgte_mmc2): beta-U · A_b · tP30 · P4_2/mnm (136) — Hallstedt 2025 mmc2 row for TETRAGONAL_U: beta-U
Candidate (tdb_comment): beta-U · tP30 · P4_2/mnm, SB: A_b — NiU-09Wan.tdb: 'Prototype beta-U (tP30, P4_2/mnm, SB: A_b)'
Stability: stable in 1 of 1 calculated diagram(s): 935–1047.02 K, x(U) 0.98983–1
Literature: 2 values (2 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:ni-u:u-tetragonal, corpus:phase:ni-u:tetragonal-u
paper: paper:10.1016/j.jallcom.2009.07.168:βU
tdb: tdb:NiU-09Wan.tdb:TETRAGONAL_U

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

NiU-09Wan.tdb: TETRAGONAL_U, type code %, sha256 9f6aef6a1ab79ad3…

48: PHASE TETRAGONAL_U % 1 1 !
49: CONST TETRAGONAL_U : NI U% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2009.07.168 C.P. Wang, Y. He, H.L. Zhang, X.J. Liu, Thermodynamic assessments of the U–Ni and Th–Ni systems, Journal of Alloys and Compounds 487, 126-131 (2009).
assessment that models this phase; reports 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}
}