# C–Zr system

> C–Zr system: 49 accepted literature values (phase transition 17, invariant reaction 17, phase equilibrium 8, formation 6) 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-ZR.html · Markdown: https://data.orchid-project.org/systems/C-ZR.md

49 accepted literature values from 2 paper(s) (experimental 33, model 13, unspecified 3); 0 calculated phase diagram(s).

Data: [JSON](https://data.orchid-project.org/literature/systems/C-ZR.json) · [CSV](https://data.orchid-project.org/systems/C-ZR.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#C-ZR) · [phases (6)](https://data.orchid-project.org/phases/pages/C-ZR.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/C-ZR.html) · [Markdown](https://data.orchid-project.org/systems/C-ZR.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 33 |
| model | 13 |
| unspecified | 3 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| invariant reaction | 17 |
| phase transition | 17 |
| phase equilibrium | 8 |
| formation | 6 |
| crystal structure | 1 |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/C/C-ZR.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/C/C-ZR.json)

## Invariant reactions (literature)

Table: Invariant reactions reported in the literature for the C–Zr system (17)

| T (K) | Reaction / phases | Compositions (mole fraction) | Class | Source | Location | Quote |
|---:|---|---|---|---|---|---|
| 3200 | γ + liquid + graphite | γ: C 0.496; L: C 0.65 | model | [1] Guillermet 1995; _cites Okamoto_ | Table 4, p. 11, row 17; `ORC-ELPBLB2H4V` |  |
| 3200 | γ + liquid + graphite | γ: C 0.495; L: C 0.676 | model | [1] Guillermet 1995 | Table 4, p. 11, row 18; `ORC-S6TJ3NKIAQ` |  |
| 3200 | γ + liquid + graphite |  | experimental | [1] Guillermet 1995; _cites ref. 63_ | Table 4, p. 11, row 15; `ORC-ZOHVV7MPQF` |  |
| 3199 | γ + liquid + graphite |  | experimental | [1] Guillermet 1995; _cites Portnoi 1961_ | Table 4, p. 11, row 3; `ORC-M5GYMWAX3U` |  |
| 3190 | γ + liquid + graphite | L: C 0.645 | experimental | [1] Guillermet 1995; _cites Rudy 1967_ | Table 4, p. 11, row 10; `ORC-N43EICWB44` |  |
| 3190 | γ + liquid + graphite | L: C 0.645 | experimental | [1] Guillermet 1995; _cites Rudy 1965_ | Table 4, p. 11, row 8; `ORC-VQLFOJPAAC` |  |
| 3189 | γ + liquid + graphite | γ: C 0.494; L: C 0.645 | experimental | [1] Guillermet 1995; _cites Rudy 1975_ | Table 4, p. 11, row 13; `ORC-WSKS4IJO5L` |  |
| 3168 | γ + liquid + graphite |  | experimental | [1] Guillermet 1995; _cites Adelsberg 1966_ | Table 4, p. 11, row 9; `ORC-HWFDGODUGD` |  |
| 3148 | γ + liquid + graphite |  | experimental | [1] Guillermet 1995; _cites Wallace 1963_ [doi](https://doi.org/10.1021/j100798a019) | Table 4, p. 11, row 5; `ORC-ZLLIL3WADQ` |  |
| 3128 | γ + liquid + graphite | γ: C 0.491 | experimental | [1] Guillermet 1995; _cites Farr 1962_ | Table 4, p. 11, row 4; `ORC-347LAAP353` |  |
| 3128 | γ + liquid + graphite | γ: C 0.49; L: C 0.65 | model | [1] Guillermet 1995; _cites Kubaschewski-von 1976_ | Table 4, p. 11, row 16; `ORC-AM43A3KNLY` |  |
| 3128 | γ + liquid + graphite | γ: C 0.491; L: C 0.65 | model | [1] Guillermet 1995; _cites Shunk 1969_ | Table 4, p. 11, row 14; `ORC-CJUE6NRG6W` |  |
| 3128 | γ + liquid + graphite | γ: C 0.491; L: C 0.65 | experimental | [1] Guillermet 1995; _cites Sara 1965_ | Table 4, p. 11, row 7; `ORC-CSSJ6UY3UZ` |  |
| 3128 | γ + liquid + graphite | γ: C 0.492; L: C 0.64 | model | [1] Guillermet 1995; _cites Storms 1967_ | Table 4, p. 11, row 11; `ORC-ONBF6GVGD6` |  |
| 3078 | γ + liquid + graphite | L: C 0.644 | experimental | [1] Guillermet 1995; _cites Chiotti 1954_ | Table 4, p. 11, row 2; `ORC-WQFXOXVDSA` |  |
| 2697 | γ + liquid + graphite |  | experimental | [1] Guillermet 1995; _cites Agte 1931_ [doi](https://doi.org/10.1002/zaac.19311980122) | Table 4, p. 11, row 1; `ORC-ZY3JEPNZOV` |  |
| 1159 | peritectoid: (βZr) + ZrC1-x \<-> (αZr) | ZrC1-x: C 0.3791; (αZr): C 0.0073; ZrC1−x: C 0.3791 | model | [2] Bittermann 2002; _cites Fernandez 1995_ [doi](https://doi.org/10.1016/0925-8388%2894%2901310-e) | Table 2, p. 5, row 5; `ORC-2JPJNDFL6T` |  |

## 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–Zr system (6)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| ZrC | [ZrC](https://data.orchid-project.org/compounds/ZrC.html) | -71 kJ/mol-atom |  | model | -77.578 (mp-aaaaaedn) | -78.347 (oqmd-4151) | [1] Guillermet 1995; _cites F 1988_ | Table 1, p. 7, row 4; `ORC-XROCL6ZLY7` |  |
| ZrC | [ZrC](https://data.orchid-project.org/compounds/ZrC.html) | -69 kJ/mol-atom |  | unspecified | -77.578 (mp-aaaaaedn) | -78.347 (oqmd-4151) | [1] Guillermet 1995 | Table 1, p. 7, row 3; `ORC-EQ2WVZB643` |  |
| ZrC0.5 | [Zr2C](https://data.orchid-project.org/compounds/Zr2C.html) | -103.5 kJ/mol-atom |  | unspecified |  | -60.373 (oqmd-2170491) | [1] Guillermet 1995 | Table 1, p. 7, row 1; `ORC-JGPZ3F5L4N` |  |
| ZrC0.5 | [Zr2C](https://data.orchid-project.org/compounds/Zr2C.html) | -103 kJ/mol-atom |  | model |  | -60.373 (oqmd-2170491) | [1] Guillermet 1995; _cites F 1988_ | Table 1, p. 7, row 2; `ORC-TO27NPPD4V` |  |
| ZrC3 | [ZrC3](https://data.orchid-project.org/compounds/ZrC3.html) | -53 kJ/mol-atom |  | model |  | 75.506 (oqmd-323488) | [1] Guillermet 1995; _cites F 1988_ | Table 1, p. 7, row 6; `ORC-7MRHG7N6JM` |  |
| ZrC3 | [ZrC3](https://data.orchid-project.org/compounds/ZrC3.html) | -25 kJ/mol-atom ± 25 |  | unspecified |  | 75.506 (oqmd-323488) | [1] Guillermet 1995 | Table 1, p. 7, row 5; `ORC-PVGKDA2GYI` |  |

## Other properties

### Phase transition (17)

Table: Phase transition, C–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 3450 K | 3450 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Friederich 1925_ [doi](https://doi.org/10.1002/zaac.19251440118) | Table 3, p. 10, row 1; `ORC-TBQ442TYKY` |  |
| Phase transition | 3455 K | 3455 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Glaser 1953_ | Table 3, p. 10, row 3; `ORC-DDVHIECVQJ` |  |
| Phase transition | 3530 K | 3530 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Wilhelm 1964_ | Table 3, p. 10, row 7; `ORC-ACDFUXGWQF` |  |
| Phase transition | 3700 K | 3700 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Shunk 1969_ | Table 3, p. 10, row 13; `ORC-3STP4JQFZV` |  |
| Phase transition | 3700 K | 3700 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Sara 1965_ | Table 3, p. 10, row 8; `ORC-5GZOBJ4IKU` |  |
| Phase transition | 3700 K | 3700 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Farr 1962_ | Table 3, p. 10, row 5; `ORC-6KGZPIXJKJ` |  |
| Phase transition | 3700 K | 3700 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Kubaschewski-von 1976_ | Table 3, p. 10, row 15; `ORC-QXYNLG7XRK` |  |
| Phase transition | 3700 K | 3700 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Storms 1967_ | Table 3, p. 10, row 10; `ORC-V2KDWMEGVG` |  |
| Phase transition | 3700 K | 3700 | congruent transformation: ZrCx (γ) congruent melting | model | [1] Guillermet 1995 | Table 3, p. 10, row 17; `ORC-X2CCF3ORHM` |  |
| Phase transition | 3720 K | 3720 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Rudy 1967_ | Table 3, p. 10, row 11; `ORC-3QB3ANG4Q6` |  |
| Phase transition | 3720 K | 3720 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Rudy 1965_ | Table 3, p. 10, row 9; `ORC-YKCAFE5XJW` |  |
| Phase transition | 3725 K | 3725 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Rudy 1975_ | Table 3, p. 10, row 12; `ORC-SA7ZCPLXCS` |  |
| Phase transition | 3784 K | 3784 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Agte 1930_ | Table 3, p. 10, row 2; `ORC-WS5MOGMHGS` |  |
| Phase transition | 3810 K | 3810 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites ref. 63_ | Table 3, p. 10, row 14; `ORC-AW4KWYTXFU` |  |
| Phase transition | 3813 K | 3813 | congruent transformation: ZrCx (γ) congruent melting | model | [1] Guillermet 1995; _cites Okamoto_ | Table 3, p. 10, row 16; `ORC-7KTKNKTROF` |  |
| Phase transition | 3816 K | 3816 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Brownlee 1959_ | Table 3, p. 10, row 4; `ORC-YJILMB5MEN` |  |
| Phase transition | 4016 K | 4016 | congruent transformation: ZrCx (γ) congruent melting | experimental | [1] Guillermet 1995; _cites Paderno 1962_ | Table 3, p. 10, row 6; `ORC-XYZPMQRYT7` |  |

### Phase equilibrium (8)

Table: Phase equilibrium, C–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase composition |  | 1136 | α + β + γ; _γ: C 0.38, Zr 0.62_ | model | [1] Guillermet 1995; _cites Okamoto_ | Table 6, p. 13, row 8; `ORC-P4IMXLCIDF` |  |
| Phase composition |  | 1139 | α + β + γ; _γ: C 0.5, Zr 0.5_ | experimental | [1] Guillermet 1995; _cites Hayes 1955_ | Table 6, p. 13, row 1; `ORC-JB2GI2LM6Y` |  |
| Phase composition |  | 1139 | α + β + γ; _γ: C 0.4, Zr 0.6_ | experimental | [1] Guillermet 1995; _cites Shunk 1969_ | Table 6, p. 13, row 6; `ORC-X7L2KRR6EV` |  |
| Phase composition |  | 1146 | α + β + γ; _γ: C 0.375, Zr 0.625_ | experimental | [1] Guillermet 1995; _cites Rudy 1965_ | Table 6, p. 13, row 4; `ORC-3W4WOQRXSZ` |  |
| Phase composition |  | 1146 | α + β + γ; _γ: C 0.4, Zr 0.6_ | experimental | [1] Guillermet 1995; _cites Kubaschewski-von 1976_ | Table 6, p. 13, row 7; `ORC-I7SE3PR6M3` |  |
| Phase composition |  | 1152.5 | α + β + γ; _α: C 0.01, Zr 0.99; β: C 0.015, Zr 0.985; γ: C 0.375, Zr 0.625_ | experimental | [1] Guillermet 1995; _cites Storms 1967_ | Table 6, p. 13, row 5; `ORC-SEOKLN2BKF` |  |
| Phase composition |  | 1159 | α + β + γ; _α: C 0.0073, Zr 0.9927; β: C 1.400e-5, Zr 0.999986; γ: C 0.379, Zr 0.621_ | model | [1] Guillermet 1995 | Table 6, p. 13, row 9; `ORC-TE234XCSZK` |  |
| Phase composition |  | 1173 | α + β + γ; _α: C 0.01, Zr 0.99; β: C 0.02, Zr 0.98; γ: C 0.36, Zr 0.64_ | experimental | [1] Guillermet 1995; _cites Benesovsky 1960_ | Table 6, p. 13, row 2; `ORC-N4CO2RCU46` |  |

### Crystal structure (1)

Table: Crystal structure, C–Zr system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Lattice a | 4.6983 Å | 298.15 | ZrC1-x; _ZrC1-x: C 0.49_ | experimental | [2] Bittermann 2002; _cites Storms 1967_ | Table 1, p. 4, row 19; `ORC-TRJ67IUJFU` |  |

## Sources

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

1. A. Fernández Guillermet, Analysis of thermochemical properties and phase stability in the zirconium-carbon system, Journal of Alloys and Compounds 217, 69-89 (1995). [doi:10.1016/0925-8388(94)01310-e](https://doi.org/10.1016/0925-8388%2894%2901310-e)
2. H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the ternary system C-Hf-Zr (Carbon-Zirconium-Hafnium), JPE 23, 218-235 (2002). [doi:10.1361/105497102770331703](https://doi.org/10.1361/105497102770331703)

## 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/).