Hf–Os phases

7 phases (tier A 5, tier C 1, liquid 1); 6 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 · Hf–Os system page · Markdown · field reference

Phases of the Hf–Os system (7)
Phase	Structure	Basis	Stability (calculated)	Literature values	TDB models
BCC_A2 phase:hf-os:bcc-a2	W · A2 · cI2 · Im-3m (229)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 1500–2450 K, x(Os) 0–0.13	4	2
B2_BCC phase:hf-os:bcc-b2	CsCl · B2 · cP2 · Pm-3m (221)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2867.72 K, x(Os) 0–0.5	6	1
FCC_A1 phase:hf-os:fcc-a1	Cu · A1 · cF4 · Fm-3m (225)	tier A: standard phase name	not stable in 1 calculated diagram(s)	0	1
HCP_A3 phase:hf-os:hcp-a3	Mg · A3 · hP2 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–3999.74 K, x(Os) 0–1	4	1
HF54OS17 phase:hf-os:hf54os17	Hf54Os17 · oI142 · Immm (71)	tier C: assessor-stated (Hallstedt 2025 crystallographic table)	stable in 1 of 1 calculated diagram(s): 300–1893.22 K, x(Os) 0.23944–0.23944	6	1
HFOS2_C14 phase:hf-os:hfos2-c14	MgZn2 · C14 · hP12 · P6_3/mmc (194)	tier A: standard phase name	stable in 1 of 1 calculated diagram(s): 300–2952.94 K, x(Os) 0.6516–0.6723	6	1
LIQUID phase:hf-os:liquid	liquid	liquid	stable in 1 of 1 calculated diagram(s): 1872.91–4000 K, x(Os) 0–1	12	1

BCC_A2 (Hf–Os)

Id: phase:hf-os: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): 1500–2450 K, x(Os) 0–0.13
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:hf-os:bcc-a2
paper: paper:10.1016/j.jallcom.2005.06.034:bcc(Hf)
tdb: tdb:HfOs-06Guo.tdb:A2_BCC, tdb:HfOs-06Guo.tdb:BCC_A2

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

HfOs-06Guo.tdb: A2_BCC, type code %B, sha256 a62b29616d7b4270…

35: PHASE A2_BCC %B 2 1 3 !
36: CONST A2_BCC : HF% OS : VA : !

HfOs-06Guo.tdb: BCC_A2, type code %B, sha256 a62b29616d7b4270…

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

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
assessment that models this phase; reports values for this phase

B2_BCC (Hf–Os)

Id: phase:hf-os:bcc-b2; status assigned
Structure: CsCl · B2 · cP2 · Pm-3m (221); type st:b2-cscl-cp2; tier A: standard phase name; confidence high
Caveat: HfOs-06Guo.tdb: ordered phase with disordered part A2_BCC (order/disorder model)
Caveat: partitioned order/disorder model in HfOs-06Guo.tdb also describes the disordered state
Stability: stable in 1 of 1 calculated diagram(s): 300–2867.72 K, x(Os) 0–0.5
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:hf-os:bcc-b2, corpus:phase:hf-os:b2-bcc
paper: paper:10.1016/j.jallcom.2005.06.034:HfOs
tdb: tdb:HfOs-06Guo.tdb:B2_BCC

TDB models of B2_BCC (1): PHASE and CONSTITUENT statements as written

HfOs-06Guo.tdb: B2_BCC, type code %BO, sha256 a62b29616d7b4270…

40: PHASE B2_BCC %BO 3 0.5 0.5 3 !
41: CONST B2_BCC : HF% OS : HF OS% : VA : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
assessment that models this phase; reports values for this phase

FCC_A1 (Hf–Os)

Id: phase:hf-os:fcc-a1; status assigned
Structure: Cu · A1 · cF4 · Fm-3m (225); type st:a1-cu-cf4; 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:hf-os:fcc-a1
tdb: tdb:HfOs-06Guo.tdb:FCC_A1

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

HfOs-06Guo.tdb: FCC_A1, type code %A, sha256 a62b29616d7b4270…

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

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
assessment that models this phase

HCP_A3 (Hf–Os)

Id: phase:hf-os: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): 300–3999.74 K, x(Os) 0–1
Literature: 4 values (4 accepted) from 1 papers
Interactive: phase registry entry

Names (4): corpus: corpus:phase:hf-os:hcp-a3
paper: paper:10.1016/j.jallcom.2005.06.034:hcp(Hf), paper:10.1016/j.jallcom.2005.06.034:hcp(Os)
tdb: tdb:HfOs-06Guo.tdb:HCP_A3

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

HfOs-06Guo.tdb: HCP_A3, type code %A, sha256 a62b29616d7b4270…

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

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
assessment that models this phase; reports values for this phase

HF54OS17 (Hf–Os)

Id: phase:hf-os:hf54os17; status assigned
Structure: Hf54Os17 · oI142 · Immm (71); type st:hf54os17-oi142; 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: Hf 0.7606, Os 0.2394
Stability: stable in 1 of 1 calculated diagram(s): 300–1893.22 K, x(Os) 0.23944–0.23944
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:hf-os:hf54os17
paper: paper:10.1016/j.jallcom.2005.06.034:Hf54Os17
tdb: tdb:HfOs-06Guo.tdb:HF54OS17

TDB models of HF54OS17 (1): PHASE and CONSTITUENT statements as written

HfOs-06Guo.tdb: HF54OS17, type code %, sha256 a62b29616d7b4270…

50: PHASE HF54OS17 % 2 54 17 !
51: CONST HF54OS17 : HF : OS : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
assessment that models this phase; reports values for this phase

HFOS2_C14 (Hf–Os)

Id: phase:hf-os:hfos2-c14; status assigned
Structure: MgZn2 · C14 · hP12 · P6_3/mmc (194); type st:c14-mgzn2-hp12; tier A: standard phase name; confidence high
Caveat: partitioned order/disorder model in HfOs-06Guo.tdb also describes the disordered state
Stability: stable in 1 of 1 calculated diagram(s): 300–2952.94 K, x(Os) 0.6516–0.6723
Literature: 6 values (6 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:hf-os:hfos2-c14
paper: paper:10.1016/j.jallcom.2005.06.034:HfOs2
tdb: tdb:HfOs-06Guo.tdb:HFOS2_C14

TDB models of HFOS2_C14 (1): PHASE and CONSTITUENT statements as written

HfOs-06Guo.tdb: HFOS2_C14, type code %, sha256 a62b29616d7b4270…

55: PHASE HFOS2_C14 % 2 1 2 !
56: CONST HFOS2_C14 : HF% OS : HF OS% : !

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
assessment that models this phase; reports values for this phase

LIQUID (Hf–Os)

Id: phase:hf-os:liquid; status assigned
Structure: liquid; type st:liquid; liquid; confidence high
Stability: stable in 1 of 1 calculated diagram(s): 1872.91–4000 K, x(Os) 0–1
Literature: 12 values (12 accepted) from 1 papers
Interactive: phase registry entry

Names (3): corpus: corpus:phase:hf-os:liquid
paper: paper:10.1016/j.jallcom.2005.06.034:L
tdb: tdb:HfOs-06Guo.tdb:LIQUID

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

HfOs-06Guo.tdb: LIQUID, type code %, sha256 a62b29616d7b4270…

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

Example references (1 of 1; assessments first):

doi:10.1016/j.jallcom.2005.06.034 Cuiping Guo, Zhenmin Du, Thermodynamic assessment of the Hf–Os system, Journal of Alloys and Compounds 407, 188-192 (2006).
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}
}