Au–Cu phases

5 phases (tier A 3, liquid 1, needs_review 1); 3 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 · Au–Cu system page · Markdown · field reference

Phases of the Au–Cu system (5)
Phase	Structure	Basis	Stability (calculated)	TDB models
BCC_A2 phase:au-cu:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
FCC_4SL phase:au-cu:fcc-4sl		needs_review	stable in 1 of 1 calculated diagram(s): 300–2499.02 K, x(Cu) 0–1	1
FCC_A1 phase:au-cu:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–1338.33 K, x(Cu) 0–0.99	2
HCP_A3 phase:au-cu:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	not stable in 1 calculated diagram(s)	1
LIQUID phase:au-cu:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1182.04–2500 K, x(Cu) 0–1	1

BCC_A2 (Au–Cu)

Id: phase:au-cu:bcc-a2; status assigned
Structure: W · A2 · cI2 · Im-3m (229); type st:a2-w-ci2; 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:au-cu:bcc-a2
tdb: tdb:AuCu-98Sun-LB.tdb:BCC_A2

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

AuCu-98Sun-LB.tdb: BCC_A2, type code %B, sha256 66a5545540f92ed9…

42: PHASE BCC_A2 %B 2 1 3 !
43: CONST BCC_A2 : AU CU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(98)00034-0 B. Sundman, S.G. Fries, A. Oates, Calphad, 22, 335-54(1998).
assessment that models this phase

FCC_4SL (Au–Cu)

Id: phase:au-cu:fcc-4sl; status needs_review
No structure assigned. Why: order_disorder_ambiguity:AuCu-98Sun-LB.tdb_model_is_partitioned; sgte_mmc2_row_disagrees_with_name:FCC_4SL; sgte_mmc2_rows_disagree; unrecognised_name_tokens:4SL
Candidate (dft_mp): Pm-3m (221) — on-hull MP Cu3Au at x(CU)=0.7500
Candidate (dft_mp): P4/mmm (123) — on-hull MP CuAu at x(CU)=0.5000
Candidate (dft_oqmd): P4/mmm (123) — on-hull OQMD Au1 Cu1 at x(CU)=0.5000
Candidate (dft_oqmd): Pm-3m (221) — on-hull OQMD Au1 Cu3 at x(CU)=0.7500
Candidate (dft_oqmd): P4/mmm (123) — on-hull OQMD Au3 Cu1 at x(CU)=0.2500
Candidate (dft_oqmd): P4/mmm (123) — on-hull OQMD Au5 Cu3 at x(CU)=0.3750
Candidate (name_token): Cu · A1 · cF4 · Fm-3m (225) — Strukturbericht/word 'A1' in the TDB name
Candidate (sgte_mmc2): AuCu · L1_0 · tP4 · P4/mmm (123) — Hallstedt 2025 mmc2 row for FCC_4SL: AlTi, AuCu, CoPt, CrPt, FeNi, FePt, MnNi
Stability: stable in 1 of 1 calculated diagram(s): 300–2499.02 K, x(Cu) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:au-cu:fcc-4sl
tdb: tdb:AuCu-98Sun-LB.tdb:FCC_4SL

TDB models of FCC_4SL (1): PHASE and CONSTITUENT statements as written

AuCu-98Sun-LB.tdb: FCC_4SL, type code %AY, sha256 66a5545540f92ed9…

37: PHASE FCC_4SL %AY 5 0.25 0.25 0.25 0.25 1 !
38: CONST FCC_4SL : AU CU : AU CU : AU CU : AU CU : VA :  !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(98)00034-0 B. Sundman, S.G. Fries, A. Oates, Calphad, 22, 335-54(1998).
assessment that models this phase

FCC_A1 (Au–Cu)

Id: phase:au-cu: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): 300–1338.33 K, x(Cu) 0–0.99
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:au-cu:fcc-a1
tdb: tdb:AuCu-98Sun-LB.tdb:A1_FCC, tdb:AuCu-98Sun-LB.tdb:FCC_A1

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

AuCu-98Sun-LB.tdb: A1_FCC, type code %A, sha256 66a5545540f92ed9…

32: PHASE A1_FCC %A 2 1 1 !
33: CONST A1_FCC : AU CU : VA : !

AuCu-98Sun-LB.tdb: FCC_A1, type code %A, sha256 66a5545540f92ed9…

27: PHASE FCC_A1 %A 2 1 1 !
28: CONST FCC_A1 : AU% CU% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(98)00034-0 B. Sundman, S.G. Fries, A. Oates, Calphad, 22, 335-54(1998).
assessment that models this phase

HCP_A3 (Au–Cu)

Id: phase:au-cu: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:au-cu:hcp-a3
tdb: tdb:AuCu-98Sun-LB.tdb:HCP_A3

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

AuCu-98Sun-LB.tdb: HCP_A3, type code %A, sha256 66a5545540f92ed9…

47: PHASE HCP_A3 %A 2 1 0.5 !
48: CONST HCP_A3 : AU CU : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(98)00034-0 B. Sundman, S.G. Fries, A. Oates, Calphad, 22, 335-54(1998).
assessment that models this phase

LIQUID (Au–Cu)

Id: phase:au-cu:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1182.04–2500 K, x(Cu) 0–1
Literature: 0 values (0 accepted) from 0 papers
Interactive: phase registry entry

Names (2): corpus: corpus:phase:au-cu:liquid
tdb: tdb:AuCu-98Sun-LB.tdb:LIQUID

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

AuCu-98Sun-LB.tdb: LIQUID, type code %, sha256 66a5545540f92ed9…

22: PHASE LIQUID:L % 1 1 !
23: CONST LIQUID:L : AU CU : !

Example references (1 of 1; assessments first):

doi:10.1016/S0364-5916(98)00034-0 B. Sundman, S.G. Fries, A. Oates, Calphad, 22, 335-54(1998).
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}
}