# C–W system

> C–W system: 32 accepted literature values (invariant reaction 24, heat capacity / entropy / enthalpy 4, formation 3, phase transition 1) and 0 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/C-W.html · Markdown: https://data.orchid-project.org/systems/C-W.md

32 accepted literature values from 2 paper(s) (experimental 12, model 20); 0 calculated phase diagram(s). 8 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: [JSON](https://data.orchid-project.org/literature/systems/C-W.json) · [CSV](https://data.orchid-project.org/systems/C-W.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#C-W) · [phases (7)](https://data.orchid-project.org/phases/pages/C-W.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/C-W.html) · [Markdown](https://data.orchid-project.org/systems/C-W.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 12 |
| model | 20 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| invariant reaction | 24 |
| phase transition | 1 |
| formation | 3 |
| heat capacity / entropy / enthalpy | 4 |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/C/C-W.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/C/C-W.json) · [CALPHAD hull WC-86Gus](https://data.orchid-project.org/hulls/calphad-sgte/C/C-W--WC-86Gus.json)

## Invariant reactions (literature)

Table: Invariant reactions reported in the literature for the C–W system (24)

| T (K) | Reaction / phases | Compositions (mole fraction) | Class | Source | Location | Quote |
|---:|---|---|---|---|---|---|
| 3051 | congruent melting: L-> hcp | L: C 0.31; hcp: C 0.31 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 5; `ORC-5PHYDCDZDS` |  |
| 3051 | congruent melting: L-> hcp | L: C 0.31; hcp: C 0.31 | model | [1] He 2022 | Table 3, p. 4, row 6; `ORC-FPQS2HPLKQ` |  |
| 3049 | L+graphite -> WC | L: C 0.42; graphite: C 1; WC: C 0.5 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 16; `ORC-3VGQZKSAN2` |  |
| 3048 | congruent melting: L-> hcp | L: C 0.31; hcp: C 0.31 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 4; `ORC-43PCBFZ6GW` |  |
| 3047 | L+graphite -> WC | L: C 0.421; graphite: C 1; WC: C 0.5 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 17; `ORC-DPX5NYI7A4` |  |
| 3045 | L+graphite -> WC | L: C 0.423; graphite: C 1; WC: C 0.5 | model | [1] He 2022 | Table 3, p. 4, row 18; `ORC-DL5DP4OQ6C` |  |
| 3020 | congruent melting: L->fcc | L: C 0.39; fcc: C 0.39 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 10; `ORC-YXRFOXPJYF` |  |
| 3008 | eutectic: L->hcp+fcc | L: C 0.365; hcp: C 0.345; fcc: C 0.375 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 7; `ORC-TZ2BUGBBDD` |  |
| 3006 | eutectic: L->hcp+fcc | L: C 0.37; hcp: C 0.323; fcc: C 0.371 | model | [1] He 2022 | Table 3, p. 4, row 9; `ORC-V6GB5K4436` |  |
| 3006 | congruent melting: L->fcc | L: C 0.373; fcc: C 0.376 | model | [1] He 2022 | Table 3, p. 4, row 12; `ORC-VOYJ7HLT5H` |  |
| 3005 | congruent melting: L->fcc | L: C 0.374; fcc: C 0.374 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 11; `ORC-XFOUVNDXWF` |  |
| 3004 | eutectic: L->hcp+fcc | L: C 0.369; hcp: C 0.323; fcc: C 0.372 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 8; `ORC-PSETSOHF27` |  |
| 3002 | eutectic: L-> fcc+WC | L: C 0.396; fcc: C 0.387; WC: C 0.5 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 14; `ORC-BOGHAM5L2K` |  |
| 3002 | eutectic: L-> fcc+WC | L: C 0.398; fcc: C 0.388; WC: C 0.5 | model | [1] He 2022 | Table 3, p. 4, row 15; `ORC-H3COJDIQJS` |  |
| 2993 | eutectic: L-> fcc+WC | L: C 0.41; fcc: C 0.395; WC: C 0.495 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 13; `ORC-QLQGFKZVOQ` |  |
| 2983 | eutectic: L->bcc+hcp | L: C 0.22; bcc: C 0.01; hcp: C 0.256 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 1; `ORC-BTLRYDOUV5` |  |
| 2983 | eutectic: L->bcc+hcp | L: C 0.2224; bcc: C 0.01; hcp: C 0.267 | model | [1] He 2022 | Table 3, p. 4, row 3; `ORC-OCOHIKWJXY` |  |
| 2980 | eutectic: L->bcc+hcp | L: C 0.2285; bcc: C 0.007; hcp: C 0.273 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 2; `ORC-3THRGH7YIT` |  |
| 2803 | fcc-> hcp+WC | fcc: C 0.38; hcp: C 0.334; WC: C 0.494 | experimental | [1] He 2022; _cites Rudy 1969_ | Table 3, p. 4, row 19; `ORC-EGF6G2KMK3` |  |
| 2803 | fcc-> hcp+WC | fcc: C 0.38; hcp: C 0.325; WC: C 0.5 | model | [1] He 2022 | Table 3, p. 4, row 21; `ORC-PUDBBM2R4M` |  |
| 2801 | fcc-> hcp+WC | fcc: C 0.38; hcp: C 0.325; WC: C 0.5 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 20; `ORC-3NNJLVPVLQ` |  |
| 1525 | hcp->bcc+WC | hcp: C 0.321; WC: C 0.5 | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 3, p. 4, row 23; `ORC-E6623TVPX7` |  |
| 1523 | hcp->bcc+WC | hcp: C 0.328; WC: C 0.5 | model | [1] He 2022 | Table 3, p. 4, row 24; `ORC-GMEF3PNNH6` |  |
| 1523 | hcp->bcc+WC | hcp: C 0.326; WC: C 0.5 | experimental | [1] He 2022; _cites Kurlov 2006_ [doi](https://doi.org/10.1134/s0020168506020051) | Table 3, p. 4, row 22; `ORC-MSZVGH54VP` |  |

## Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from [dft_parity.json](https://data.orchid-project.org/literature/dft_parity.json).

Table: Enthalpies of formation, C–W system (3)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| WC |  | -40170 per formula unit ± 1700 | 298.15 | experimental |  |  | [1] He 2022; _cites McGraw 1947_ [doi](https://doi.org/10.1021/ja01194a050) | Table 2, p. 3, row 4; `ORC-QU6UWVFZOZ` |  |
| WC | [WC](https://data.orchid-project.org/compounds/WC.html) | -20.0887 kJ/mol-atom | 298.15 | model | -11.742 (mp-aaaaacuw) | -12.124 (oqmd-3084) | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 2, p. 3, row 5; `ORC-VO2SJGX55E` |  |
| WC | [WC](https://data.orchid-project.org/compounds/WC.html) | -20.0852 kJ/mol-atom | 298.15 | model | -11.742 (mp-aaaaacuw) | -12.124 (oqmd-3084) | [1] He 2022 | Table 2, p. 3, row 6; `ORC-YPBYQ7YY6I` |  |

## Other properties

### Phase transition (1)

Table: Phase transition, C–W system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 3020 K | 3020 | congruent transformation | experimental | [2] Gustafson 1986 | p. 3; `ORC-KLDQLY65LG.e2b404` | “Rudy et al. show peritectic melting of WC at 3049 ± 4 K in contact with graphite while WC1-x melts congruently at 3020± 12 K.” |

### Heat capacity / entropy / enthalpy (4)

Table: Heat capacity / entropy / enthalpy, C–W system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Entropy; _printed: S^WC(298)_ | 16.045 J/mol-atom/K | 298.15 | WC; _alloy: W 0.5_ | experimental | [1] He 2022; _cites McGraw 1947_ [doi](https://doi.org/10.1021/ja01194a050) | Table 2, p. 3, row 1; `ORC-P5CQER2LTC` |  |
| Entropy; _printed: S^WC(298)_ | 16.05 J/mol-atom/K | 298.15 | WC; _alloy: W 0.5_ | model | [1] He 2022 | Table 2, p. 3, row 3; `ORC-UITIZVU2HA` |  |
| Entropy; _printed: S^WC(298)_ | 16.045 J/mol-atom/K | 298.15 | WC; _alloy: W 0.5_ | model | [1] He 2022; _cites Gustafson 1986_ [doi](https://doi.org/10.1016/0008-6223%2886%2990113-2) | Table 2, p. 3, row 2; `ORC-UP3NCW543B` |  |
| Entropy; _printed: standard entropy_ | 159.8 J/(mol K) | 1000 | W2 C0.833 (hcp) | experimental | [1] He 2022; _cites Grnvold 1988_ [doi](https://doi.org/10.1016/0040-6031%2888%2987202-2) | p. 3; `ORC-JS4CWKZJG3` | “Grønvold et al. \[40\] determined the standard entropy of W2 C0.833 (hcp) to be 75.80 J/(mol K) at 298.15 K and 159.8 J/(mol K) at 1000 K.” |

## Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

1. Zhangting He, Malin Selleby, A third generation Calphad description of W–C including a revision of liquid C, Calphad 78, 102449 (2022). [doi:10.1016/j.calphad.2022.102449](https://doi.org/10.1016/j.calphad.2022.102449)
2. P. Gustafson, Thermodynamic evaluation of C–W system, Materials Science and Technology 2, 653-658 (1986). [doi:10.1179/mst.1986.2.7.653](https://doi.org/10.1179/mst.1986.2.7.653)

## Please cite

- R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735569
- R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). https://doi.org/10.5281/zenodo.23735891
- R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); 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); 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.

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.

```bibtex
@misc{orchid_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_hulls_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD)}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735891},
  url       = {https://doi.org/10.5281/zenodo.23735891}
}

@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}
}
```

---

Derived data CC BY 4.0 ([licence](https://creativecommons.org/licenses/by/4.0/)): cite ORCHID ([CITATION.cff](https://data.orchid-project.org/CITATION.cff)) and the original sources. Quotes are short excerpts kept so that each value can be checked; they remain under the publishers' copyright and are not relicensed. Source papers, page images and full text are not redistributed. Field reference: [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt). Found an error? The report link of a value (Markdown: its id, ORC-..., in the Location column) opens a pre-filled GitHub issue, https://github.com/orchid-calphad/orchid-data/issues/new?template=report-value-error.yml&record_id=\<id>, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).