# Cu–Hf system

> Cu–Hf system: 156 accepted literature values (invariant reaction 62, formation 54, crystal structure 29, phase transition 11) and 3 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/CU-HF.html · Markdown: https://data.orchid-project.org/systems/CU-HF.md

156 accepted literature values from 3 paper(s) (experimental 58, model 56, DFT 17, unspecified 25); 3 calculated phase diagram(s). 9 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/CU-HF.json) · [CSV](https://data.orchid-project.org/systems/CU-HF.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#CU-HF) · [interactive phase diagram](https://orchid-project.org/phase-diagrams/#CU-HF/CuHf-06Lia.json) · [phases (9)](https://data.orchid-project.org/phases/pages/CU-HF.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/CU-HF.html) · [Markdown](https://data.orchid-project.org/systems/CU-HF.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 58 |
| model | 56 |
| DFT | 17 |
| unspecified | 25 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| invariant reaction | 62 |
| phase transition | 11 |
| formation | 54 |
| crystal structure | 29 |

## Calculated phase diagrams

Binary phase diagrams calculated with pycalphad 0.11.2 from the SGTE binary collection (Hallstedt 2025, CC BY 4.0). Evidence class: model.

Table: Assessments with a calculated phase diagram

| TDB file | Assessment | SHA-256 | Links |
|---|---|---|---|
| CuHf-06Lia.tdb | D. Liang, Y. Liu, J. Alloys Compd., 426, 101-5(2006). [doi:10.1016/j.jallcom.2006.02.013](https://doi.org/10.1016/j.jallcom.2006.02.013) | `0c635db89455db2193d2338dc7c2c7254656d48062f08f84dc42892948b58442` | [viewer](https://orchid-project.org/phase-diagrams/#CU-HF/CuHf-06Lia.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/CuHf-06Lia.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/CuHf-06Lia.json) |
| CuHf-08Tur.tdb | M.A. Turchanin, P.G. Agraval, Powder Metall. Met. Ceram., 47, 223-33(2008). [doi:10.1007/s11106-008-9008-4](https://doi.org/10.1007/s11106-008-9008-4) | `06d472151340d413caab538d0c986d4360544f591246ec54e843796570015f0d` | [viewer](https://orchid-project.org/phase-diagrams/#CU-HF/CuHf-08Tur.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/CuHf-08Tur.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/CuHf-08Tur.json) |
| CuHf-13Zho.tdb | Y. Zhong, A. Saengdeejing, L. Kecskes. B. Klotz, Z.-K. Liu, Acta Mater., 61, 660-69(2013). [doi:10.1016/j.actamat.2012.10.014](https://doi.org/10.1016/j.actamat.2012.10.014) | `e3133d3e66ab9d10462b3945eeb6ffe7f2f660a143f1f84efa8cd389c04aa7b5` | [viewer](https://orchid-project.org/phase-diagrams/#CU-HF/CuHf-13Zho.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/CuHf-13Zho.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/CuHf-13Zho.json) |

Table: Calculated three-phase invariants (model, mole fraction of the second component)

| TDB file | T (K) | Phases at the invariant |
|---|---:|---|
| CuHf-06Lia.tdb | 1813.67 | LIQUID (x(Hf) 0.78938) + BCC_A2 (x(Hf) 0.95737) + HCP_A3 (x(Hf) 0.99582) |
| CuHf-06Lia.tdb | 1556.36 | CUHF2 (x(Hf) 0.66667) + LIQUID (x(Hf) 0.72905) + HCP_A3 (x(Hf) 0.99379) |
| CuHf-06Lia.tdb | 1556.36 | CUHF2 (x(Hf) 0.66667) + LIQUID (x(Hf) 0.729) + HCP_A3 (x(Hf) 0.99379) |
| CuHf-06Lia.tdb | 1326.8 | LIQUID (x(Hf) 0.13783) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-06Lia.tdb | 1326.8 | LIQUID (x(Hf) 0.13807) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-06Lia.tdb | 1326.8 | LIQUID (x(Hf) 0.13776) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-06Lia.tdb | 1263.85 | CU51HF14 (x(Hf) 0.21538) + CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.33244) |
| CuHf-06Lia.tdb | 1263.85 | CU51HF14 (x(Hf) 0.21538) + CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.33228) |
| CuHf-06Lia.tdb | 1252.99 | CU10HF7 (x(Hf) 0.41176) + LIQUID (x(Hf) 0.43637) + CUHF2 (x(Hf) 0.66667) |
| CuHf-06Lia.tdb | 1252.99 | CU10HF7 (x(Hf) 0.41176) + LIQUID (x(Hf) 0.43657) + CUHF2 (x(Hf) 0.66667) |
| CuHf-06Lia.tdb | 1235.87 | FCC_A1 (x(Hf) 0.00276) + LIQUID (x(Hf) 0.0754) + CU5HF_C15B (x(Hf) 0.16667) |
| CuHf-06Lia.tdb | 1235.87 | FCC_A1 (x(Hf) 0.00275) + LIQUID (x(Hf) 0.07535) + CU5HF_C15B (x(Hf) 0.16667) |
| CuHf-06Lia.tdb | 1233.92 | CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.35681) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-06Lia.tdb | 1233.92 | CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.35693) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-08Tur.tdb | 1815.4 | LIQUID (x(Hf) 0.77753) + BCC_A2 (x(Hf) 0.9556) + HCP_A3 (x(Hf) 0.99695) |
| CuHf-08Tur.tdb | 1552.62 | CUHF2 (x(Hf) 0.66667) + LIQUID (x(Hf) 0.74041) + HCP_A3 (x(Hf) 0.99773) |
| CuHf-08Tur.tdb | 1313.2 | LIQUID (x(Hf) 0.09743) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-08Tur.tdb | 1278.48 | FCC_A1 (x(Hf) 0.00279) + LIQUID (x(Hf) 0.06787) + CU5HF_C15B (x(Hf) 0.16667) |
| CuHf-08Tur.tdb | 1262.38 | CU51HF14 (x(Hf) 0.21538) + CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.38443) |
| CuHf-08Tur.tdb | 1255.81 | CU10HF7 (x(Hf) 0.41176) + LIQUID (x(Hf) 0.42092) + CUHF2 (x(Hf) 0.66667) |
| CuHf-08Tur.tdb | 1254.11 | CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.39199) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-08Tur.tdb | 321.43 | CU51HF14 (x(Hf) 0.21538) + CU8HF3 (x(Hf) 0.27273) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-13Zho.tdb | 1812.79 | LIQUID (x(Hf) 0.80631) + BCC_A2 (x(Hf) 0.95774) + HCP_A3 (x(Hf) 0.99908) |
| CuHf-13Zho.tdb | 1571.42 | CUHF2 (x(Hf) 0.66667) + LIQUID (x(Hf) 0.72279) + HCP_A3 (x(Hf) 0.99886) |
| CuHf-13Zho.tdb | 1571.42 | CUHF2 (x(Hf) 0.66667) + LIQUID (x(Hf) 0.72274) + HCP_A3 (x(Hf) 0.99886) |
| CuHf-13Zho.tdb | 1332.63 | LIQUID (x(Hf) 0.13278) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-13Zho.tdb | 1332.63 | LIQUID (x(Hf) 0.13307) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-13Zho.tdb | 1332.63 | LIQUID (x(Hf) 0.13262) + CU5HF_C15B (x(Hf) 0.16667) + CU51HF14 (x(Hf) 0.21538) |
| CuHf-13Zho.tdb | 1279.43 | LIQUID (x(Hf) 0.40546) + CU10HF7 (x(Hf) 0.41176) + CUHF2 (x(Hf) 0.66667) |
| CuHf-13Zho.tdb | 1279.43 | LIQUID (x(Hf) 0.40583) + CU10HF7 (x(Hf) 0.41176) + CUHF2 (x(Hf) 0.66667) |
| CuHf-13Zho.tdb | 1274.49 | CU51HF14 (x(Hf) 0.21538) + CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.3478) |
| CuHf-13Zho.tdb | 1274.49 | CU51HF14 (x(Hf) 0.21538) + CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.34766) |
| CuHf-13Zho.tdb | 1263.37 | CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.35891) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-13Zho.tdb | 1263.37 | CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.3588) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-13Zho.tdb | 1263.37 | CU8HF3 (x(Hf) 0.27273) + LIQUID (x(Hf) 0.35903) + CU10HF7 (x(Hf) 0.41176) |
| CuHf-13Zho.tdb | 1255.51 | FCC_A1 (x(Hf) 0.0042) + LIQUID (x(Hf) 0.07067) + CU5HF_C15B (x(Hf) 0.16667) |
| CuHf-13Zho.tdb | 1255.51 | FCC_A1 (x(Hf) 0.0042) + LIQUID (x(Hf) 0.07062) + CU5HF_C15B (x(Hf) 0.16667) |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/CU/CU-HF.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/CU/CU-HF.json) · [CALPHAD hull CuHf-06Lia](https://data.orchid-project.org/hulls/calphad-sgte/CU/CU-HF--CuHf-06Lia.json) · [CALPHAD hull CuHf-08Tur](https://data.orchid-project.org/hulls/calphad-sgte/CU/CU-HF--CuHf-08Tur.json)

## Invariant reactions (literature)

Table: Invariant reactions reported in the literature for the Cu–Hf system (62)

| T (K) | Reaction / phases | Compositions (mole fraction) | Class | Source | Location | Quote |
|---:|---|---|---|---|---|---|
| 1819 | bcc = liquid + hcp | bcc: Hf 0.958; liquid: Hf 0.806; hcp: Hf 0.999 | model | [1] Zhong 2013 | Table 4, p. 9, row 17; `ORC-55IUYWATJZ` |  |
| 1815 | (βHf) \<=> L + (αHf) | (βHf): Hf 0.997; L: Hf 0.778; (αHf): Hf 0.956 | model | [2] Turchanin 2008 | Table 1, p. 4, row 11; `ORC-4MO47TQBGQ` |  |
| 1813.7 | bcc -> liquid + hcp | bcc: Hf 0.96; liquid: Hf 0.7894; hcp: Hf 0.996 | model | [3] Liang 2006 | Table 2, p. 3, row 19; `ORC-5QLVRWPOAR` |  |
| 1813 | bcc -> liquid + hcp | bcc: Hf 0.957; liquid: Hf 0.8; hcp: Hf 0.991 | experimental | [3] Liang 2006; _cites Pieraggi 1974_ [doi](https://doi.org/10.1016/0022-3115%2874%2990184-6) | Table 2, p. 3, row 20; `ORC-D2VKUFG2JD` |  |
| 1813 | (βHf) \<=> L + (αHf) | (βHf): Hf 0.991; (αHf): Hf 0.957 | experimental | [2] Turchanin 2008; _cites ref. 11_ | Table 1, p. 4, row 10; `ORC-UCDVTRL5HQ` |  |
| 1813 | bcc = liquid + hcp | bcc: Hf 0.957; liquid: Hf 0.8; hcp: Hf 0.991 | experimental | [1] Zhong 2013; _cites Pieraggi 1974_ [doi](https://doi.org/10.1016/0022-3115%2874%2990184-6) | Table 4, p. 9, row 18; `ORC-ZOXQIMZJDE` |  |
| 1611 | congruent melting: L \<=> CuHf2 | L: Hf 0.6667; CuHf2: Hf 0.6667 | model | [2] Turchanin 2008 | Table 1, p. 4, row 6; `ORC-Z5QDQQZ2T2` |  |
| 1583 | congruent melting: L \<=> CuHf2 | L: Hf 0.6667; CuHf2: Hf 0.6667 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 4, row 5; `ORC-NZYPJUJPWH` |  |
| 1571 | Liquid = CuHf2 + hcp | Liquid: Hf 0.723; CuHf2: Hf 0.667; hcp: Hf 0.999 | model | [1] Zhong 2013 | Table 4, p. 9, row 15; `ORC-HRXVVMODAL` |  |
| 1568.15 | eutectic: liquid -> hcp + CuHf2 |  | experimental | [3] Liang 2006; _cites Pieraggi 1974_ [doi](https://doi.org/10.1016/0022-3115%2874%2990184-6) | p. 2; `ORC-WEMWGRB35N` | “Pieraggi et al. \[17\] studied the Hf-rich portion of the Cu-Hf system between 72.7 and 100 at.% Hf using DTA and metallography. It was discovered that the eutectic decomposition of the liquid Cu-Hf alloy into hcp and CuHf2 appeared at 1295 ◦ C.” |
| 1568 | eutectic: Liquid -> CuHf2 + hcp | L: Hf 0.732; CuHf2: Hf 0.666667 | experimental | [1] Zhong 2013; _cites Pieraggi 1974_ [doi](https://doi.org/10.1016/0022-3115%2874%2990184-6) | Table 4, p. 9, row 26; `ORC-DFWQPHO3Q4` |  |
| 1568 | L \<=> CuHf2 + (αHf) | CuHf2: Hf 0.6667 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 4, row 7; `ORC-E5BDWDIQBL` |  |
| 1568 | eutectic: Liquid -> CuHf2 + hcp | L: Hf 0.72; CuHf2: Hf 0.666667 | experimental | [1] Zhong 2013; _cites Markiv 1974_ | Table 4, p. 9, row 25; `ORC-FOYULYGYDR` |  |
| 1568 | eutectic: Liquid -> CuHf2 + hcp | Liquid: Hf 0.732; CuHf2: Hf 0.666667 | experimental | [3] Liang 2006; _cites Pieraggi 1974_ [doi](https://doi.org/10.1016/0022-3115%2874%2990184-6) | Table 2, p. 3, row 18; `ORC-QRFHOPCJTC` |  |
| 1568 | L \<=> CuHf2 + (αHf) | CuHf2: Hf 0.6667; (αHf): Hf 0.997 | experimental | [2] Turchanin 2008; _cites ref. 11_ | Table 1, p. 4, row 8; `ORC-RJTLLHMRI2` |  |
| 1556.4 | eutectic: Liquid -> CuHf2 + hcp | Liquid: Hf 0.729; CuHf2: Hf 0.666667 | model | [3] Liang 2006 | Table 2, p. 3, row 17; `ORC-LDQNY4MX2K` |  |
| 1552 | L \<=> CuHf2 + (αHf) | L: Hf 0.74; CuHf2: Hf 0.6667; (αHf): Hf 0.998 | model | [2] Turchanin 2008 | Table 1, p. 4, row 9; `ORC-ZVIKGM7H4T` |  |
| 1385 | congruent melting: L -> Cu51Hf14 | L: Hf 0.2154; Cu51Hf14: Hf 0.2154 | model | [2] Turchanin 2008 | Table 1, p. 3, row 9; `ORC-XOHVWYJM4V` |  |
| 1383 | congruent melting: L -> Cu51Hf14 | L: Hf 0.25; Cu51Hf14: Hf 0.25 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 3, row 8; `ORC-7PFNC5LICO` |  |
| 1333 | Cu5Hf = liquid + Cu51Hf14 | Cu5Hf: Hf 0.167; liquid: Hf 0.133; Cu51Hf14: Hf 0.215 | model | [1] Zhong 2013 | Table 4, p. 9, row 3; `ORC-CYOX6CKSX7` |  |
| 1328 | Cu5Hf = liquid + Cu51Hf14 | Cu5Hf: Hf 0.166667; liquid: Hf 0.126; Cu51Hf14: Hf 0.215385 | experimental | [1] Zhong 2013; _cites Perry 1974_ [doi](https://doi.org/10.1016/0025-5416%2874%2990021-4) | Table 4, p. 9, row 4; `ORC-242K5MNAXP` |  |
| 1328 | L + Cu51Hf14 -> Cu5Hf | Cu51Hf14: Cu 0.784615, Hf 0.215385; Cu5Hf: Hf 0.1667 | experimental | [2] Turchanin 2008; _cites ref. 9_ | Table 1, p. 3, row 6; `ORC-BGK662SYQO` |  |
| 1328 | Cu5Hf -> liquid + Cu51Hf14 | Cu5Hf: Hf 0.166667; liquid: Hf 0.126; Cu51Hf14: Hf 0.215385 | experimental | [3] Liang 2006; _cites Perry 1974_ [doi](https://doi.org/10.1016/0025-5416%2874%2990021-4) | Table 2, p. 3, row 4; `ORC-LVVSWSPY2M` |  |
| 1326.8 | Cu5Hf -> liquid + Cu51Hf14 | Cu5Hf: Hf 0.166667; liquid: Hf 0.138; Cu51Hf14: Hf 0.215385 | model | [3] Liang 2006 | Table 2, p. 3, row 3; `ORC-LJN4WPAEMS` |  |
| 1313 | L + Cu51Hf14 -> Cu5Hf | L: Hf 0.097; Cu51Hf14: Hf 0.2154; Cu5Hf: Hf 0.1667 | model | [2] Turchanin 2008 | Table 1, p. 3, row 7; `ORC-IALY4PYBLA` |  |
| 1298 | Cu10Hf7 = Liquid + CuHf2 | Cu10Hf7: Hf 0.411765; Liquid: Hf 0.4; CuHf2: Hf 0.666667 | experimental | [1] Zhong 2013; _cites Woodman 2006_ [doi](https://doi.org/10.1007/bf02736446) | Table 4, p. 9, row 12; `ORC-LQUULBZFZ4` |  |
| 1288 | congruent melting: L \<=> Cu10Hf7 | L: Hf 0.4; Cu10Hf7: Hf 0.4 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 4, row 1; `ORC-JHXUZQRXT4` |  |
| 1279 | Cu10Hf7 = Liquid + CuHf2 | Cu10Hf7: Hf 0.412; Liquid: Hf 0.405; CuHf2: Hf 0.667 | model | [1] Zhong 2013 | Table 4, p. 9, row 11; `ORC-U65MFYMEA2` |  |
| 1278 | eutectic: L -> (Cu) + Cu5Hf | L: Hf 0.068; (Cu): Hf 0.003; Cu5Hf: Hf 0.1667 | model | [2] Turchanin 2008 | Table 1, p. 3, row 5; `ORC-NQDLWLY3UJ` |  |
| 1275 | peritectic: liquid + CuHf2 = Cu10 Hf7 |  | experimental | [1] Zhong 2013 | p. 4; `ORC-M2JPEVEPRB` | “Nevertheless, the invariant temperature for the peritectic reaction liquid + CuHf2 = Cu10 Hf7 was determined to be 1275 K.” |
| 1275 | Cu10Hf7 -> Liquid + CuHf2 | Cu10Hf7: Hf 0.411765; CuHf2: Hf 0.666667 | experimental | [1] Zhong 2013 | Table 4, p. 9, row 24; `ORC-YNWXNBHLYP` |  |
| 1274 | Cu8Hf3 = Cu51Hf14 + liquid | Cu8Hf3: Hf 0.273; Cu51Hf14: Hf 0.215; liquid: Hf 0.348 | model | [1] Zhong 2013 | Table 4, p. 9, row 7; `ORC-3PDML3E4EV` |  |
| 1263.8 | Cu8Hf3 -> Cu51Hf14 + liquid | Cu8Hf3: Hf 0.272727; Cu51Hf14: Hf 0.215385; liquid: Hf 0.332 | model | [3] Liang 2006 | Table 2, p. 3, row 7; `ORC-OVHP2SVISB` |  |
| 1263 | L + Cu51Hf14 -> Cu8Hf3 | Cu51Hf14: Hf 0.25; Cu8Hf3: Hf 0.2857 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 3, row 10; `ORC-2BMZWDMNQD` |  |
| 1263 | L + Cu51Hf14 -> Cu8Hf3 | L: Hf 0.384; Cu51Hf14: Hf 0.2154; Cu8Hf3: Hf 0.2727 | model | [2] Turchanin 2008 | Table 1, p. 3, row 12; `ORC-2PU2CUQEG7` |  |
| 1263 | Liquid = Cu8Hf3 + Cu10Hf7 | Liquid: Hf 0.359; Cu8Hf3: Hf 0.273; Cu10Hf7: Hf 0.412 | model | [1] Zhong 2013 | Table 4, p. 9, row 9; `ORC-3J4QV3EVYT` |  |
| 1263 | Cu8Hf3 = Cu51Hf14 + liquid | Cu8Hf3: Hf 0.272727; Cu51Hf14: Hf 0.215385; liquid: Hf 0.34 | experimental | [1] Zhong 2013; _cites Markiv 1974_ | Table 4, p. 9, row 8; `ORC-5J37RFZYAF` |  |
| 1263 | L + Cu51Hf14 -> Cu8Hf3 | L: Hf 0.33; Cu51Hf14: Hf 0.2154; Cu8Hf3: Hf 0.2727 | model | [2] Turchanin 2008; _cites ref. 13_ | Table 1, p. 3, row 11; `ORC-CC5GF2IP3F` |  |
| 1263 | Cu8Hf3 -> Cu51Hf14 + liquid | Cu8Hf3: Hf 0.272727; Cu51Hf14: Hf 0.215385; liquid: Hf 0.34 | experimental | [3] Liang 2006; _cites Subramanian 1988_ [doi](https://doi.org/10.1007/bf02877460) | Table 2, p. 3, row 8; `ORC-OU5XXROYDO` |  |
| 1261 | Liquid = Cu51Hf14 + Cu10Hf7 | Liquid: Hf 0.355; Cu51Hf14: Hf 0.215; Cu10Hf7: Hf 0.412 | model | [1] Zhong 2013 | Table 4, p. 9, row 19; `ORC-FXKFFM6CWY` |  |
| 1261 | eutectic: L -> (Cu) + Cu5Hf | L: Hf 0.0775; Cu5Hf: Hf 0.1667 | experimental | [2] Turchanin 2008; _cites ref. 9_ | Table 1, p. 3, row 3; `ORC-JVIC7UWMSZ` |  |
| 1261 | eutectic: Liquid -> fcc + Cu5Hf | L: Hf 0.078; Cu5Hf: Hf 0.166667 | experimental | [1] Zhong 2013; _cites Perry 1974_ [doi](https://doi.org/10.1016/0025-5416%2874%2990021-4) | Table 4, p. 9, row 21; `ORC-W5EKEQ5FVK` |  |
| 1256 | congruent melting: L \<=> Cu10Hf7 | L: Hf 0.4118; Cu10Hf7: Hf 0.4118 | model | [2] Turchanin 2008 | Table 1, p. 4, row 2; `ORC-227FJ7IAPN` |  |
| 1256 | Liquid = fcc + Cu5Hf | Liquid: Hf 0.071; fcc: Hf 0.004; Cu5Hf: Hf 0.167 | model | [1] Zhong 2013 | Table 4, p. 9, row 1; `ORC-H27UO5FMLO` |  |
| 1255 | L \<=> Cu10Hf7 + CuHf2 | L: Hf 0.421; Cu10Hf7: Hf 0.4118; CuHf2: Hf 0.6667 | model | [2] Turchanin 2008 | Table 1, p. 4, row 4; `ORC-EOCKAFJTOQ` |  |
| 1254 | eutectic: L -> Cu8Hf3 + Cu10Hf7 | L: Hf 0.392; Cu8Hf3: Hf 0.2727; Cu10Hf7: Hf 0.4118 | model | [2] Turchanin 2008 | Table 1, p. 3, row 14; `ORC-F6VZ65TEXX` |  |
| 1253.15 | eutectic |  | experimental | [3] Liang 2006; _cites Perry 1974_ [doi](https://doi.org/10.1016/0025-5416%2874%2990021-4) | p. 2; `ORC-RMWY5A6JMO` | “Perry et al. \[18\] established the Cu-rich end of the Cu-Hf system by DTA, metallography and electron microprobe analysis. A terminal eutectic between fcc solid solution and Cu5 Hf at 7.75 at.% Hf and 980 ◦ C was observed, which is in disagreement with the data of Markiv et al. \[15\].” |
| 1253 | L \<=> Cu10Hf7 + CuHf2 | L: Hf 0.436; Cu10Hf7: Hf 0.4; CuHf2: Hf 0.6667 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 4, row 3; `ORC-3GYMD4KJTQ` |  |
| 1253 | eutectic: Liquid -> Cu10Hf7 + CuHf2 | Liquid: Hf 0.436; Cu10Hf7: Hf 0.411765; CuHf2: Hf 0.666667 | experimental | [3] Liang 2006; _cites Subramanian 1988_ [doi](https://doi.org/10.1007/bf02877460) | Table 2, p. 3, row 14; `ORC-3ORZP4VGO7` |  |
| 1253 | eutectic: Liquid -> Cu10Hf7 + CuHf2 | Liquid: Hf 0.436; Cu10Hf7: Hf 0.411765; CuHf2: Hf 0.666667 | model | [3] Liang 2006 | Table 2, p. 3, row 13; `ORC-UX3TUZEEWW` |  |
| 1250 | eutectic: Liquid -> fcc + Cu5Hf | fcc: Hf 0.003; Cu5Hf: Hf 0.166667 | experimental | [1] Zhong 2013; _cites Watanabe 1967_ | Table 4, p. 9, row 20; `ORC-DA4PGALPBA` |  |
| 1243 | eutectic: L -> Cu8Hf3 + Cu10Hf7 | L: Hf 0.366; Cu8Hf3: Hf 0.2857; Cu10Hf7: Hf 0.4 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 3, row 13; `ORC-G6REIZZ2BE` |  |
| 1243 | eutectic: Liquid -> fcc + Cu5Hf | fcc: Hf 0.003; Cu5Hf: Hf 0.166667 | experimental | [1] Zhong 2013; _cites Saarivirta 1963_ | Table 4, p. 9, row 23; `ORC-JRDVKLRKPF` |  |
| 1243 | Liquid = Cu8Hf3 + Cu10Hf7 | Liquid: Hf 0.386; Cu8Hf3: Hf 0.272727; Cu10Hf7: Hf 0.411765 | experimental | [1] Zhong 2013; _cites Markiv 1974_ | Table 4, p. 9, row 10; `ORC-T426QSDSEY` |  |
| 1243 | eutectic: L -> (Cu) + Cu5Hf | (Cu): Hf 0.0034; Cu5Hf: Cu 0.833333, Hf 0.166667 | experimental | [2] Turchanin 2008; _cites ref. 8_ | Table 1, p. 3, row 2; `ORC-UBDOONWDUO` |  |
| 1243 | eutectic: Liquid -> Cu8Hf3 + Cu10Hf7 | Liquid: Hf 0.386; Cu8Hf3: Hf 0.272727; Cu10Hf7: Hf 0.411765 | experimental | [3] Liang 2006; _cites Subramanian 1988_ [doi](https://doi.org/10.1007/bf02877460) | Table 2, p. 3, row 10; `ORC-WF7Q3SE2BS` |  |
| 1238 | eutectic: L -> (Cu) + Cu5Hf | (Cu): Hf 0.0031; Cu5Hf: Cu 0.833333, Hf 0.166667 | experimental | [2] Turchanin 2008; _cites ref. 7_ | Table 1, p. 3, row 1; `ORC-QDFYKKZJ6S` |  |
| 1235.9 | eutectic: Liquid -> fcc + Cu5Hf | Liquid: Hf 0.075; fcc: Hf 0.003; Cu5Hf: Hf 0.166667 | model | [3] Liang 2006 | Table 2, p. 3, row 1; `ORC-6TCDSTYUS2` |  |
| 1233.9 | eutectic: Liquid -> Cu8Hf3 + Cu10Hf7 | Liquid: Hf 0.357; Cu8Hf3: Hf 0.272727; Cu10Hf7: Hf 0.411765 | model | [3] Liang 2006 | Table 2, p. 3, row 9; `ORC-KRLAN4J7IR` |  |
| 1223 | eutectic: Liquid -> fcc + Cu5Hf | Liquid: Hf 0.078; fcc: Hf 0; Cu5Hf: Hf 0.166667 | experimental | [3] Liang 2006; _cites Markiv 1974_ | Table 2, p. 3, row 2; `ORC-RFDSLQN5UX` |  |
| 1223 | eutectic: Liquid -> fcc + Cu5Hf | L: Hf 0.078; Cu5Hf: Hf 0.166667 | experimental | [1] Zhong 2013; _cites Markiv 1974_ | Table 4, p. 9, row 22; `ORC-SDDGUTQRBO` |  |
| 1223 | eutectic: L -> (Cu) + Cu5Hf | L: Hf 0.06; Cu5Hf: Cu 0.833333, Hf 0.166667 | experimental | [2] Turchanin 2008; _cites ref. 10_ | Table 1, p. 3, row 4; `ORC-WZJBQK2WSR` |  |

## 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, Cu–Hf system (49)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| Cu10Hf7 |  | -19.2 kJ/mol-atom |  | DFT |  |  | [1] Zhong 2013; _cites Ghosh 2007_ [doi](https://doi.org/10.1016/j.actamat.2007.01.037) | Table 2, p. 7, row 18; `ORC-O37ALFLERL.9b94c3` |  |
| Cu10Hf7 |  | -18.73 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 19; `ORC-ZJA3T3IAMD.1f21b1` |  |
| Cu10Hf7 |  | -16.42 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 20; `ORC-CSJHRFNNEC.2c74cd` |  |
| Cu10Hf7 | [Cu10Hf7](https://data.orchid-project.org/compounds/Cu10Hf7.html) | -16 kJ/mol-atom |  | model | -17.211 (mp-aaacqipw) | -16.705 (oqmd-2052356) | [1] Zhong 2013; _cites Turchanin 2008_ [doi](https://doi.org/10.1007/s11106-008-9008-4) | Table 2, p. 7, row 17; `ORC-6H4GCYSRVL.53d0fd` |  |
| Cu10Hf7 | [Cu10Hf7](https://data.orchid-project.org/compounds/Cu10Hf7.html) | -15.5 kJ/mol-atom |  | model | -17.211 (mp-aaacqipw) | -16.705 (oqmd-2052356) | [1] Zhong 2013; _cites Liang 2006_ [doi](https://doi.org/10.1016/j.jallcom.2006.02.013) | Table 2, p. 7, row 16; `ORC-DICKHYYEVP.69896d` |  |
| Cu10Hf7 |  | -15.499 kJ/mol (basis unstated) | 298.15 | model |  |  | [2] Turchanin 2008 | Table 2, p. 6, row 11; `ORC-CHVOUIL3BY.d36735` |  |
| Cu10Hf7 |  | -12.64 kJ/mol (basis unstated) ± 0.49 | 298.15 | experimental |  |  | [2] Turchanin 2008; _cites ref. 20_ | Table 2, p. 6, row 9; `ORC-FEUZZU5CX3` |  |
| Cu10Hf7 | [Cu10Hf7](https://data.orchid-project.org/compounds/Cu10Hf7.html) | -12.64 kJ/mol-atom | 298.15 | experimental | -17.211 (mp-aaacqipw) | -16.705 (oqmd-2052356) | [1] Zhong 2013; _cites Kleppa 1982_ [doi](https://doi.org/10.1007/bf02667755) | Table 2, p. 7, row 14; `ORC-HU6TGEN7ZU.a8618c` |  |
| Cu10Hf7 |  | -4.15 kJ/mol (basis unstated) | 298.15 | unspecified |  |  | [2] Turchanin 2008; _cites ref. 13_ | Table 2, p. 6, row 10; `ORC-6LCYHKLJMC` |  |
| Cu10Hf7 | [Cu10Hf7](https://data.orchid-project.org/compounds/Cu10Hf7.html) | -4.15 kJ/mol-atom |  | model | -17.211 (mp-aaacqipw) | -16.705 (oqmd-2052356) | [1] Zhong 2013; _cites Subramanian 1988_ | Table 2, p. 7, row 15; `ORC-NBO4YVSDLI.253d5d` |  |
| Cu51Hf14 | [Cu51Hf14](https://data.orchid-project.org/compounds/Cu51Hf14.html) | -45.54 kJ/mol-atom | 298.15 | unspecified | -15.029 (mp-aaacrrua) |  | [2] Turchanin 2008; _cites ref. 13_ | Table 2, p. 6, row 5; `ORC-B3OHX5SB4Z` |  |
| Cu51Hf14 | [Cu51Hf14](https://data.orchid-project.org/compounds/Cu51Hf14.html) | -45.54 kJ/mol-atom |  | model | -15.029 (mp-aaacrrua) |  | [1] Zhong 2013; _cites Subramanian 1988_ | Table 2, p. 7, row 22; `ORC-HREA4KXIA5.7a851a` |  |
| Cu51Hf14 |  | -22.9 kJ/mol (basis unstated) ± 2300 | 298.15 | experimental |  |  | [2] Turchanin 2008; _cites ref. 25_ | Table 2, p. 6, row 4; `ORC-VSAFTWBZSP` |  |
| Cu51Hf14 |  | -16.02 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 26; `ORC-Y4OPMYTL73.3b3c80` |  |
| Cu51Hf14 |  | -14.83 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 27; `ORC-35VGTOXXIK.2f0d62` |  |
| Cu51Hf14 | [Cu51Hf14](https://data.orchid-project.org/compounds/Cu51Hf14.html) | -13.65 kJ/mol-atom | 298.15 | experimental | -15.029 (mp-aaacrrua) |  | [1] Zhong 2013; _cites Kleppa 1982_ [doi](https://doi.org/10.1007/bf02667755) | Table 2, p. 7, row 21; `ORC-BRWKD672OZ.90c952` |  |
| Cu51Hf14 |  | -13.65 kJ/mol (basis unstated) ± 240 | 298.15 | experimental |  |  | [2] Turchanin 2008; _cites ref. 20_ | Table 2, p. 6, row 3; `ORC-QLGFU74OUC` |  |
| Cu51Hf14 | [Cu51Hf14](https://data.orchid-project.org/compounds/Cu51Hf14.html) | -12.871 kJ/mol-atom | 298.15 | model | -15.029 (mp-aaacrrua) |  | [2] Turchanin 2008 | Table 2, p. 6, row 6; `ORC-RC5VYALIVL.f46af1` |  |
| Cu51Hf14 | [Cu51Hf14](https://data.orchid-project.org/compounds/Cu51Hf14.html) | -12.87 kJ/mol-atom |  | model | -15.029 (mp-aaacrrua) |  | [1] Zhong 2013; _cites Liang 2006_ [doi](https://doi.org/10.1016/j.jallcom.2006.02.013) | Table 2, p. 7, row 23; `ORC-BANPRJ3Q3M.7d31fe` |  |
| Cu51Hf14 | [Cu51Hf14](https://data.orchid-project.org/compounds/Cu51Hf14.html) | -12.46 kJ/mol-atom |  | model | -15.029 (mp-aaacrrua) |  | [1] Zhong 2013; _cites Turchanin 2008_ [doi](https://doi.org/10.1007/s11106-008-9008-4) | Table 2, p. 7, row 24; `ORC-XBUJP7GXLN.7f8f6a` |  |
| Cu51Hf14 |  | -7.91 kJ/mol-atom |  | DFT |  |  | [1] Zhong 2013; _cites Ghosh 2007_ [doi](https://doi.org/10.1016/j.actamat.2007.01.037) | Table 2, p. 7, row 25; `ORC-AEZCNSGQLU.aa445d` |  |
| Cu54Hf14 |  | -7.37 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 28; `ORC-CSUTXAAKBW.5d83f6` |  |
| Cu54Hf14 |  | -6.07 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 29; `ORC-43XXWNSX7A.90f41f` |  |
| Cu5Hf | [Cu5Hf](https://data.orchid-project.org/compounds/Cu5Hf.html) | -17.75 kJ/mol-atom |  | model |  | -11.585 (oqmd-1373519) | [1] Zhong 2013; _cites Subramanian 1988_ | Table 2, p. 7, row 30; `ORC-G7C7WZM7FM.196545` |  |
| Cu5Hf |  | -17.75 kJ/mol (basis unstated) | 298.15 | unspecified |  |  | [2] Turchanin 2008; _cites ref. 13_ | Table 2, p. 6, row 1; `ORC-JDCEQ4WV7C` |  |
| Cu5Hf |  | -12.31 kJ/mol-atom |  | DFT |  |  | [1] Zhong 2013; _cites Ghosh 2007_ [doi](https://doi.org/10.1016/j.actamat.2007.01.037) | Table 2, p. 7, row 33; `ORC-MG5BNPQIGK.32bee1` |  |
| Cu5Hf |  | -11.99 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 34; `ORC-MLF2T4WWK4.73c56d` |  |
| Cu5Hf |  | -11.69 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 35; `ORC-FRA3IWZIDU.3acf38` |  |
| Cu5Hf | [Cu5Hf](https://data.orchid-project.org/compounds/Cu5Hf.html) | -9.91 kJ/mol-atom |  | model |  | -11.585 (oqmd-1373519) | [1] Zhong 2013; _cites Liang 2006_ [doi](https://doi.org/10.1016/j.jallcom.2006.02.013) | Table 2, p. 7, row 31; `ORC-BL3VUR3FCA.531d80` |  |
| Cu5Hf |  | -9.909 kJ/mol (basis unstated) | 298.15 | model |  |  | [2] Turchanin 2008 | Table 2, p. 6, row 2; `ORC-WFG7YQVC6A.b1f104` |  |
| Cu5Hf | [Cu5Hf](https://data.orchid-project.org/compounds/Cu5Hf.html) | -9.62 kJ/mol-atom |  | model |  | -11.585 (oqmd-1373519) | [1] Zhong 2013; _cites Turchanin 2008_ [doi](https://doi.org/10.1007/s11106-008-9008-4) | Table 2, p. 7, row 32; `ORC-FZKBN7XXHG.89c6ae` |  |
| Cu8Hf3 |  | -192.72 kJ/mol (basis unstated) | 298.15 | unspecified |  |  | [2] Turchanin 2008; _cites ref. 13_ | Table 2, p. 6, row 7; `ORC-3CSEBKHBQH` |  |
| Cu8Hf3 | [Cu8Hf3](https://data.orchid-project.org/compounds/Cu8Hf3.html) | -192.72 kJ/mol-atom |  | model | -16.068 (mp-aaaaakwv) | -15.567 (oqmd-32345) | [1] Zhong 2013; _cites Subramanian 1988_ | Table 2, p. 7, row 8; `ORC-HRJTWRGIKE.c68ad1` |  |
| Cu8Hf3 |  | -17.27 kJ/mol-atom |  | DFT |  |  | [1] Zhong 2013; _cites Ghosh 2007_ [doi](https://doi.org/10.1016/j.actamat.2007.01.037) | Table 2, p. 7, row 11; `ORC-IHKCRADOGP.644147` |  |
| Cu8Hf3 |  | -16.74 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 12; `ORC-HYLK6422AN.054b67` |  |
| Cu8Hf3 |  | -15.22 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 13; `ORC-2L4O3RZVBW.513fa5` |  |
| Cu8Hf3 |  | -13.629 kJ/mol (basis unstated) | 298.15 | model |  |  | [2] Turchanin 2008 | Table 2, p. 6, row 8; `ORC-3TT6CRWE4Y.1927ef` |  |
| Cu8Hf3 | [Cu8Hf3](https://data.orchid-project.org/compounds/Cu8Hf3.html) | -13.6 kJ/mol-atom |  | model | -16.068 (mp-aaaaakwv) | -15.567 (oqmd-32345) | [1] Zhong 2013; _cites Liang 2006_ [doi](https://doi.org/10.1016/j.jallcom.2006.02.013) | Table 2, p. 7, row 9; `ORC-O6LHIWXOYM.6829ec` |  |
| Cu8Hf3 | [Cu8Hf3](https://data.orchid-project.org/compounds/Cu8Hf3.html) | -13.55 kJ/mol-atom |  | model | -16.068 (mp-aaaaakwv) | -15.567 (oqmd-32345) | [1] Zhong 2013; _cites Turchanin 2008_ [doi](https://doi.org/10.1007/s11106-008-9008-4) | Table 2, p. 7, row 10; `ORC-F5YMZB3DG4.082379` |  |
| CuHf2 | [CuHf2](https://data.orchid-project.org/compounds/CuHf2.html) | -56.12 kJ/mol-atom |  | model | -15.432 (mp-aaaabtgf) | -15.582 (oqmd-1895392) | [1] Zhong 2013; _cites Subramanian 1988_ | Table 2, p. 7, row 2; `ORC-LFFAURRWJR.279709` |  |
| CuHf2 |  | -56.12 kJ/mol (basis unstated) | 298.15 | unspecified |  |  | [2] Turchanin 2008; _cites ref. 13_ | Table 2, p. 6, row 13; `ORC-WRO7MSQFXC` |  |
| CuHf2 | [CuHf2](https://data.orchid-project.org/compounds/CuHf2.html) | -20.75 kJ/mol-atom |  | model | -15.432 (mp-aaaabtgf) | -15.582 (oqmd-1895392) | [1] Zhong 2013; _cites Turchanin 2008_ [doi](https://doi.org/10.1007/s11106-008-9008-4) | Table 2, p. 7, row 4; `ORC-QJULZWCIEL.278e8d` |  |
| CuHf2 |  | -19.174 kJ/mol (basis unstated) | 298.15 | model |  |  | [2] Turchanin 2008 | Table 2, p. 6, row 14; `ORC-3WTY5H37JD.2c7cce` |  |
| CuHf2 | [CuHf2](https://data.orchid-project.org/compounds/CuHf2.html) | -19.17 kJ/mol-atom |  | model | -15.432 (mp-aaaabtgf) | -15.582 (oqmd-1895392) | [1] Zhong 2013; _cites Liang 2006_ [doi](https://doi.org/10.1016/j.jallcom.2006.02.013) | Table 2, p. 7, row 3; `ORC-W5WGTMDOHB.756772` |  |
| CuHf2 |  | -16.36 kJ/mol-atom |  | DFT |  |  | [1] Zhong 2013; _cites Ghosh 2007_ [doi](https://doi.org/10.1016/j.actamat.2007.01.037) | Table 2, p. 7, row 5; `ORC-LZMH32MA65.59d25b` |  |
| CuHf2 |  | -16.22 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 6; `ORC-I6SVGJPAHK.b240cd` |  |
| CuHf2 |  | -15.5 kJ/mol-atom | 0 | DFT |  |  | [1] Zhong 2013 | Table 2, p. 7, row 7; `ORC-7OJKQR5NMN.64a4de` |  |
| CuHf2 | [CuHf2](https://data.orchid-project.org/compounds/CuHf2.html) | -15.23 kJ/mol-atom | 298.15 | experimental | -15.432 (mp-aaaabtgf) | -15.582 (oqmd-1895392) | [1] Zhong 2013; _cites Kleppa 1982_ [doi](https://doi.org/10.1007/bf02667755) | Table 2, p. 7, row 1; `ORC-5MXBBIBV47.8b3ef0` |  |
| CuHf2 |  | -15.23 kJ/mol (basis unstated) ± 0.5 | 298.15 | experimental |  |  | [2] Turchanin 2008; _cites ref. 20_ | Table 2, p. 6, row 12; `ORC-FNWXM3BG5X` |  |

## Other properties

### Phase transition (11)

Table: Phase transition, Cu–Hf system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 1257.8 K | 1257.8 | Cu10Hf7 -> liquid; _Cu10Hf7: Hf 0.411765; liquid: Hf 0.411765_ | model | [3] Liang 2006 | Table 2, p. 3, row 11; `ORC-I5ZOH3S4JT` |  |
| Phase transition | 1298 K | 1298 | Cu10Hf7 -> liquid; _Cu10Hf7: Hf 0.411765; liquid: Hf 0.411765_ | experimental | [3] Liang 2006; _cites Subramanian 1988_ [doi](https://doi.org/10.1007/bf02877460) | Table 2, p. 3, row 12; `ORC-JHHS2RIT2O` |  |
| Phase transition | 1383 K | 1383 | Cu51Hf14 = liquid; _Cu51Hf14: Hf 0.215385; liquid: Hf 0.215385_ | experimental | [1] Zhong 2013; _cites Markiv 1974_ | Table 4, p. 9, row 6; `ORC-XXZN75GZHA` |  |
| Phase transition | 1385 K | 1385 | Cu51Hf14 = liquid; _Cu51Hf14: Hf 0.215; liquid: Hf 0.215_ | model | [1] Zhong 2013 | Table 4, p. 9, row 5; `ORC-AKB6E6F63N` |  |
| Phase transition | 1388 K | 1388 | Cu51Hf14 -> liquid; _Cu51Hf14: Hf 0.215385; liquid: Hf 0.215385_ | experimental | [3] Liang 2006; _cites Subramanian 1988_ [doi](https://doi.org/10.1007/bf02877460) | Table 2, p. 3, row 6; `ORC-SFPVPZQ4RI` |  |
| Phase transition | 1388 K | 1388 | Cu51Hf14 -> liquid; _Cu51Hf14: Hf 0.215385; liquid: Hf 0.215385_ | model | [3] Liang 2006 | Table 2, p. 3, row 5; `ORC-YEUNAVYET7` |  |
| Phase transition | 1583 K | 1583 | CuHf2 -> liquid; _CuHf2: Hf 0.666667; liquid: Hf 0.666667_ | experimental | [3] Liang 2006; _cites Markiv 1974_ | Table 2, p. 3, row 16; `ORC-OVFHCWVUAA` |  |
| Phase transition | 1583 K | 1583 | CuHf2 = liquid; _CuHf2: Hf 0.666667; liquid: Hf 0.666667_ | experimental | [1] Zhong 2013; _cites Markiv 1974_ | Table 4, p. 9, row 14; `ORC-Q4EXSVQI2V` |  |
| Phase transition | 1583.7 K | 1583.7 | CuHf2 -> liquid; _CuHf2: Hf 0.666667; liquid: Hf 0.666667_ | model | [3] Liang 2006 | Table 2, p. 3, row 15; `ORC-EA6AFJSOQE` |  |
| Phase transition | 1589 K | 1589 | CuHf2 = liquid; _CuHf2: Hf 0.667; liquid: Hf 0.667_ | model | [1] Zhong 2013 | Table 4, p. 9, row 13; `ORC-77HKTZL35Q` |  |
| Phase transition | 1813.15 K | 1813.15 | other: bcc -> hcp + liquid | experimental | [3] Liang 2006; _cites Pieraggi 1974_ [doi](https://doi.org/10.1016/0022-3115%2874%2990184-6) | p. 2; `ORC-4BUTTSOGNH` | “Also, the metatectic decomposition temperature of bcc into hcp and liquid was determined to be 1540 ◦ C.” |

### Formation (5)

Table: Formation, Cu–Hf system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Entropy of formation; _printed: ΔfS_ | -2.213 J/mol (basis unstated)/K | 298.15 | Cu10Hf7; _alloy: Hf 0.411765_ | model | [2] Turchanin 2008 | Table 2, p. 6, row 11; `ORC-CHVOUIL3BY.a34310` |  |
| Entropy of formation; _printed: ΔfS_ | -2 J/mol-atom/K | 298.15 | Cu51Hf14; _alloy: Hf 0.215385_ | model | [2] Turchanin 2008 | Table 2, p. 6, row 6; `ORC-RC5VYALIVL.836431` |  |
| Entropy of formation; _printed: ΔfS_ | -1.37 J/mol (basis unstated)/K | 298.15 | Cu5Hf; _alloy: Hf 0.166667_ | model | [2] Turchanin 2008 | Table 2, p. 6, row 2; `ORC-WFG7YQVC6A.0d5221` |  |
| Entropy of formation; _printed: ΔfS_ | -2.028 J/mol (basis unstated)/K | 298.15 | Cu8Hf3; _alloy: Hf 0.272727_ | model | [2] Turchanin 2008 | Table 2, p. 6, row 8; `ORC-3TT6CRWE4Y.d190b6` |  |
| Entropy of formation; _printed: ΔfS_ | -3.383 J/mol (basis unstated)/K | 298.15 | CuHf2; _alloy: Hf 0.666667_ | model | [2] Turchanin 2008 | Table 2, p. 6, row 14; `ORC-3WTY5H37JD.74a744` |  |

### Crystal structure (29)

Table: Crystal structure, Cu–Hf system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Lattice a | 9.2785 not_printed |  | Cu10Hf7; _alloy: Hf 0.411765_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 4; `ORC-WRYOOWWIRX.b825c1` |  |
| Lattice a | 11.2319 not_printed |  | Cu51Hf14; _alloy: Hf 0.215385_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 2; `ORC-WJAN4CQ7RQ.346a85` |  |
| Lattice a | 6.873 not_printed |  | Cu5Hf; _alloy: Hf 0.166667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 1; `ORC-KO5HZVOVZY.4c8672` |  |
| Lattice a | 7.8444 not_printed |  | Cu8Hf3; _alloy: Hf 0.272727_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 3; `ORC-NV44I4BETM.5ca9ca` |  |
| Lattice a | 3.1631 not_printed |  | CuHf2; _alloy: Hf 0.666667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 5; `ORC-GUOPGQ2MFL.7fc47c` |  |
| Lattice a | 11.18 not_printed | 298.15 | Cu51Hf14; _alloy: Hf 0.215385_ | experimental | [1] Zhong 2013; _cites Gabathuler 1975_ [doi](https://doi.org/10.1107/s0567740875003378) | Table 1, p. 6, row 6; `ORC-E25VVGY4YC.adb6d9` |  |
| Lattice a | 7.8113 not_printed | 298.15 | Cu8Hf3; _alloy: Hf 0.272727_ | experimental | [1] Zhong 2013; _cites Bsenko 1975_ [doi](https://doi.org/10.1016/0022-5088%2875%2990085-5) | Table 1, p. 6, row 7; `ORC-CKOOEMS4TV.d523ac` |  |
| Lattice a | 3.1695 not_printed | 298.15 | CuHf2; _alloy: Hf 0.666667_ | experimental | [1] Zhong 2013; _cites Nevitt 1962_ | Table 1, p. 6, row 8; `ORC-HONM4L2INM.c7a960` |  |
| Lattice b | 12.6294 not_printed |  | Cu10Hf7; _alloy: Hf 0.411765_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 4; `ORC-WRYOOWWIRX.e1dec5` |  |
| Lattice b | 11.2319 not_printed |  | Cu51Hf14; _alloy: Hf 0.215385_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 2; `ORC-WJAN4CQ7RQ.b302ba` |  |
| Lattice b | 6.873 not_printed |  | Cu5Hf; _alloy: Hf 0.166667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 1; `ORC-KO5HZVOVZY.3187c7` |  |
| Lattice b | 8.1426 not_printed |  | Cu8Hf3; _alloy: Hf 0.272727_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 3; `ORC-NV44I4BETM.704aa6` |  |
| Lattice b | 3.1631 not_printed |  | CuHf2; _alloy: Hf 0.666667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 5; `ORC-GUOPGQ2MFL.a083e6` |  |
| Lattice b | 11.18 not_printed | 298.15 | Cu51Hf14; _alloy: Hf 0.215385_ | experimental | [1] Zhong 2013; _cites Gabathuler 1975_ [doi](https://doi.org/10.1107/s0567740875003378) | Table 1, p. 6, row 6; `ORC-E25VVGY4YC.c874b1` |  |
| Lattice b | 8.1014 not_printed | 298.15 | Cu8Hf3; _alloy: Hf 0.272727_ | experimental | [1] Zhong 2013; _cites Bsenko 1975_ [doi](https://doi.org/10.1016/0022-5088%2875%2990085-5) | Table 1, p. 6, row 7; `ORC-CKOOEMS4TV.b5e625` |  |
| Lattice b | 3.1695 not_printed | 298.15 | CuHf2; _alloy: Hf 0.666667_ | experimental | [1] Zhong 2013; _cites Nevitt 1962_ | Table 1, p. 6, row 8; `ORC-HONM4L2INM.0233f8` |  |
| Lattice c | 9.3148 not_printed |  | Cu10Hf7; _alloy: Hf 0.411765_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 4; `ORC-WRYOOWWIRX.133414` |  |
| Lattice c | 8.2905 not_printed |  | Cu51Hf14; _alloy: Hf 0.215385_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 2; `ORC-WJAN4CQ7RQ.1315b3` |  |
| Lattice c | 6.873 not_printed |  | Cu5Hf; _alloy: Hf 0.166667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 1; `ORC-KO5HZVOVZY.1985fb` |  |
| Lattice c | 9.9788 not_printed |  | Cu8Hf3; _alloy: Hf 0.272727_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 3; `ORC-NV44I4BETM.70e588` |  |
| Lattice c | 11.134 not_printed |  | CuHf2; _alloy: Hf 0.666667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 5; `ORC-GUOPGQ2MFL.d90a9b` |  |
| Lattice c | 8.235 not_printed | 298.15 | Cu51Hf14; _alloy: Hf 0.215385_ | experimental | [1] Zhong 2013; _cites Gabathuler 1975_ [doi](https://doi.org/10.1107/s0567740875003378) | Table 1, p. 6, row 6; `ORC-E25VVGY4YC.d32c5a` |  |
| Lattice c | 9.947 not_printed | 298.15 | Cu8Hf3; _alloy: Hf 0.272727_ | experimental | [1] Zhong 2013; _cites Bsenko 1975_ [doi](https://doi.org/10.1016/0022-5088%2875%2990085-5) | Table 1, p. 6, row 7; `ORC-CKOOEMS4TV.13be9d` |  |
| Lattice c | 11.1333 not_printed | 298.15 | CuHf2; _alloy: Hf 0.666667_ | experimental | [1] Zhong 2013; _cites Nevitt 1962_ | Table 1, p. 6, row 8; `ORC-HONM4L2INM.260a20` |  |
| lattice volume | 16.052 Å3 atom−1 |  | Cu10Hf7; _alloy: Hf 0.411765_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 4; `ORC-WRYOOWWIRX.6a9bac` |  |
| lattice volume | 13.935 Å3 atom−1 |  | Cu51Hf14; _alloy: Hf 0.215385_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 2; `ORC-WJAN4CQ7RQ.a4cf35` |  |
| lattice volume | 13.534 Å3 atom−1 |  | Cu5Hf; _alloy: Hf 0.166667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 1; `ORC-KO5HZVOVZY.a56b35` |  |
| lattice volume | 14.486 Å3 atom−1 |  | Cu8Hf3; _alloy: Hf 0.272727_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 3; `ORC-NV44I4BETM.dd959c` |  |
| lattice volume | 18.566 Å3 atom−1 |  | CuHf2; _alloy: Hf 0.666667_ | unspecified | [1] Zhong 2013 | Table 1, p. 6, row 5; `ORC-GUOPGQ2MFL.5f590f` |  |

## Sources

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

1. Yu Zhong, Arkapol Saengdeejing, Laszlo Kecskes, Bradley Klotz, Zi-Kui Liu, Experimental and computational studies of the Cu–Hf binary system, Acta Materialia 61, 660-669 (2013). [doi:10.1016/j.actamat.2012.10.014](https://doi.org/10.1016/j.actamat.2012.10.014)
2. M. A. Turchanin, P. G. Agraval, Thermodynamic assessment of the copper-hafnium system, Powder Metall Met Ceram 47, 223-233 (2008). [doi:10.1007/s11106-008-9008-4](https://doi.org/10.1007/s11106-008-9008-4)
3. Dong Liang, Yajun Liu, Reevaluation of the Cu–Hf binary system, Journal of Alloys and Compounds 426, 101-105 (2006). [doi:10.1016/j.jallcom.2006.02.013](https://doi.org/10.1016/j.jallcom.2006.02.013)

## 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-Diagrams: calculated binary phase diagrams (version 2026.10), Zenodo (2026). https://doi.org/10.5281/zenodo.23735859
- 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); 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).

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_phase_diagrams_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Diagrams: calculated binary phase diagrams}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735859},
  url       = {https://doi.org/10.5281/zenodo.23735859}
}

@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/).