# Fe–Ta system

> Fe–Ta system: 238 accepted literature values (invariant reaction 91, phase transition 71, formation 36, crystal structure 27) and 3 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/FE-TA.html · Markdown: https://data.orchid-project.org/systems/FE-TA.md

238 accepted literature values from 3 paper(s) (experimental 139, model 79, DFT 6, unspecified 14); 3 calculated phase diagram(s). 13 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/FE-TA.json) · [CSV](https://data.orchid-project.org/systems/FE-TA.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#FE-TA) · [interactive phase diagram](https://orchid-project.org/phase-diagrams/#FE-TA/FeTa-03Dan.json) · [phases (7)](https://data.orchid-project.org/phases/pages/FE-TA.html) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/FE-TA.html) · [Markdown](https://data.orchid-project.org/systems/FE-TA.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 139 |
| model | 79 |
| DFT | 6 |
| unspecified | 14 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| invariant reaction | 91 |
| phase transition | 71 |
| phase equilibrium | 13 |
| formation | 36 |
| crystal structure | 27 |

## 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 |
|---|---|---|---|
| FeTa-03Dan.tdb | A. Danon, C. Servant, J. Nucl. Mater., 321, 8-18(2003). [doi:10.1016/S0022-3115(03)00196-X](https://doi.org/10.1016/S0022-3115%2803%2900196-X) | `e83eaadd3887295a5f92ef703e966351adfb91fead60026a2997abf7ea7b634e` | [viewer](https://orchid-project.org/phase-diagrams/#FE-TA/FeTa-03Dan.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/FeTa-03Dan.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/FeTa-03Dan.json) |
| FeTa-11Wit.tdb | V.T. Witusiewicz, A.A. Bondar, U. Hecht, V.M. Voblikov, O.S. Fomichov, V.M. Petyukh, S. Rex, Intermetallics, 19, 1059-75(2011). [doi:10.1016/j.intermet.2011.03.018](https://doi.org/10.1016/j.intermet.2011.03.018) | `9f4e7036b7ede1950b6bc64e77320f0bb4f0ac9b5707eac3b6d6026b9991ff90` | [viewer](https://orchid-project.org/phase-diagrams/#FE-TA/FeTa-11Wit.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/FeTa-11Wit.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/FeTa-11Wit.json) |
| FeTa-15Raj.tdb | V.B. Rajkumar, K.C. Hari Kumar, Calphad, 48, 157-65(2015). [doi:10.1016/j.calphad.2014.12.006](https://doi.org/10.1016/j.calphad.2014.12.006) | `04b06f96f96efcaab9397bde62b5d8a6ba78612bc41a66ceedfd36f465a9831b` | [viewer](https://orchid-project.org/phase-diagrams/#FE-TA/FeTa-15Raj.json) · [TDB](https://orchid-project.org/data/databases/sgte-binary/FeTa-15Raj.tdb) · [JSON](https://data.orchid-project.org/phase-diagrams/sgte/FeTa-15Raj.json) |

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

| TDB file | T (K) | Phases at the invariant |
|---|---:|---|
| FeTa-03Dan.tdb | 2047.05 | C14_LAVES (x(Ta) 0.4099) + LIQUID (x(Ta) 0.41839) + MU_D85 (x(Ta) 0.49261) |
| FeTa-03Dan.tdb | 2042.38 | MU_D85 (x(Ta) 0.59771) + LIQUID (x(Ta) 0.63653) + BCC_A2 (x(Ta) 0.93968) |
| FeTa-03Dan.tdb | 1725.65 | BCC_A2 (x(Ta) 0.04236) + LIQUID (x(Ta) 0.06859) + C14_LAVES (x(Ta) 0.27205) |
| FeTa-03Dan.tdb | 1493.46 | FCC_A1 (x(Ta) 0.01052) + BCC_A2 (x(Ta) 0.01513) + C14_LAVES (x(Ta) 0.26982) |
| FeTa-03Dan.tdb | 1198.62 | FCC_A1 (x(Ta) 0.00108) + BCC_A2 (x(Ta) 0.00219) + C14_LAVES (x(Ta) 0.27858) |
| FeTa-11Wit.tdb | 2058.91 | C14_LAVES (x(Ta) 0.41006) + MU_D85 (x(Ta) 0.51095) + LIQUID (x(Ta) 0.51743) |
| FeTa-11Wit.tdb | 2023.92 | MU_D85 (x(Ta) 0.60372) + LIQUID (x(Ta) 0.65184) + BCC_A2 (x(Ta) 0.91414) |
| FeTa-11Wit.tdb | 1716.11 | BCC_A2 (x(Ta) 0.02091) + LIQUID (x(Ta) 0.07473) + C14_LAVES (x(Ta) 0.27679) |
| FeTa-11Wit.tdb | 1510.75 | FCC_A1 (x(Ta) 0.01061) + BCC_A2 (x(Ta) 0.01496) + C14_LAVES (x(Ta) 0.2977) |
| FeTa-11Wit.tdb | 1242.43 | FCC_A1 (x(Ta) 0.00409) + BCC_A2 (x(Ta) 0.00786) + C14_LAVES (x(Ta) 0.3186) |
| FeTa-15Raj.tdb | 2064.99 | C14_LAVES (x(Ta) 0.42799) + MU_D85 (x(Ta) 0.49686) + LIQUID (x(Ta) 0.50673) |
| FeTa-15Raj.tdb | 2015.22 | MU_D85 (x(Ta) 0.61526) + LIQUID (x(Ta) 0.65031) + BCC_A2 (x(Ta) 0.92232) |
| FeTa-15Raj.tdb | 1720.87 | BCC_A2 (x(Ta) 0.02284) + LIQUID (x(Ta) 0.06293) + C14_LAVES (x(Ta) 0.29834) |
| FeTa-15Raj.tdb | 1503.7 | FCC_A1 (x(Ta) 0.00917) + BCC_A2 (x(Ta) 0.01559) + C14_LAVES (x(Ta) 0.3101) |
| FeTa-15Raj.tdb | 1245.19 | FCC_A1 (x(Ta) 0.00392) + BCC_A2 (x(Ta) 0.00836) + C14_LAVES (x(Ta) 0.32176) |

Convex hulls: [Materials Project DFT hull](https://data.orchid-project.org/hulls/dft-mp/FE/FE-TA.json) · [OQMD DFT hull](https://data.orchid-project.org/hulls/dft-oqmd/FE/FE-TA.json) · [CALPHAD hull FeTa-03Dan](https://data.orchid-project.org/hulls/calphad-sgte/FE/FE-TA--FeTa-03Dan.json) · [CALPHAD hull FeTa-11Wit](https://data.orchid-project.org/hulls/calphad-sgte/FE/FE-TA--FeTa-11Wit.json)

## Invariant reactions (literature)

Table: Invariant reactions reported in the literature for the Fe–Ta system (91)

| T (K) | Reaction / phases | Compositions (mole fraction) | Class | Source | Location | Quote |
|---:|---|---|---|---|---|---|
| 2157.15 | other: μ ↔ Liq. | Liq.: Ta 0.5382; μ ↔ Liq.: Ta 0.5382 | model | [1] Danon 2003; _cites Coelho 1994_ | Table 1, p. 5, row 2; `ORC-ACN7C56MF4` |  |
| 2143.15 | other: μ ↔ Liq. | Liq.: Ta 0.516; μ ↔ Liq.: Ta 0.516 | experimental | [1] Danon 2003; _cites Swartzendruber 1990_ | Table 1, p. 5, row 1; `ORC-TDD5UJW5XW` |  |
| 2089.15 | peritectic: Liq. + μ ↔ ε | μ: Ta 0.5079; ε: Ta 0.4362; L: Ta 0.4288 | model | [1] Danon 2003; _cites Coelho 1994_ | Table 1, p. 5, row 5; `ORC-6NHBFELSNX` |  |
| 2065 | L + ε -> μ | L: Ta 0.5067; ε: Ta 0.428; μ: Ta 0.4969 | model | [2] Rajkumar 2015 | Table 2, p. 3, row 6; `ORC-UHQKCUBWST` |  |
| 2061.15 | other: μ ↔ Liq. | Liq.: Ta 0.52; μ ↔ Liq.: Ta 0.52 | model | [1] Danon 2003 | Table 1, p. 5, row 4; `ORC-NSBPYUZENN` |  |
| 2060 | peritectic: L + λ \<-> μ | L: Ta 0.516; λ: Ta 0.409; μ: Ta 0.511 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 7; `ORC-6WIAOSCRGF` |  |
| 2056 | peritectic: L + λ \<-> μ | λ: Ta 0.424; μ: Ta 0.49 | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 6; `ORC-LOZ7M5RXV6` |  |
| 2056 | L + ε -> μ | ε: Ta 0.424; μ: Ta 0.49 | unspecified | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 2, p. 3, row 5; `ORC-ZJQHTZGKOS` |  |
| 2049.15 | other: μ ↔ Liq. | Liq.: Ta 0.5384; μ ↔ Liq.: Ta 0.5384 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 5, row 3; `ORC-FNTZC3CNXE` |  |
| 2048.15 | other: ε ↔ Liq. | Liq.: Ta 0.326; ε ↔ Liq.: Ta 0.326 | experimental | [1] Danon 2003; _cites Elliot 1958_ | Table 1, p. 5, row 6; `ORC-XF2IVSVL3P` |  |
| 2047.15 | other: ε ↔ Liq. | Liq.: Ta 0.386; ε ↔ Liq.: Ta 0.386 | model | [1] Danon 2003 | Table 1, p. 5, row 8; `ORC-VGBBVM2KX4` |  |
| 2046.15 | eutectic: ε + μ ↔ Liq. | ε: Ta 0.41; μ: Ta 0.493; L: Ta 0.419 | model | [1] Danon 2003 | Table 1, p. 5, row 14; `ORC-J6H2ZS74GA` |  |
| 2042.15 | eutectic: Liq. ↔ μ + bcc | μ: Ta 0.598; bcc: Ta 0.94; L: Ta 0.636 | model | [1] Danon 2003 | Table 1, p. 5, row 11; `ORC-JQC7SX362P` |  |
| 2042 | eutectic: L \<-> β + μ | L: Ta 0.638; β: Ta 0.94; μ: Ta 0.598 | model | [3] Witusiewicz 2011; _cites Danon 2003_ [doi](https://doi.org/10.1016/s0921-5093%2802%2900632-9) | Table 6, p. 14, row 15; `ORC-4UFOCXNVWG` |  |
| 2035.15 | other: ε ↔ Liq. | Liq.: Ta 0.33; ε ↔ Liq.: Ta 0.33 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 5, row 7; `ORC-KOV6M3PUZW` |  |
| 2035 | eutectic: L \<-> β + μ | L: Ta 0.66; β: Ta 0.915; μ: Ta 0.61 | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 12; `ORC-5ZGRITLTFX` |  |
| 2035 | eutectic: L -> μ + (Ta) | L: Ta 0.66; μ: Ta 0.61; (Ta): Ta 0.915 | unspecified | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 2, p. 3, row 8; `ORC-MEHV6XDC6W` |  |
| 2025 | eutectic: L \<-> β + Ta3Fe2 | L: Ta 0.653; β: Ta 0.914; Ta3Fe2: Ta 0.628 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 10; `ORC-PDGZTALKSI.3b711a` |  |
| 2025 | eutectic: L \<-> β + μ | L: Ta 0.652; β: Ta 0.914; μ: Ta 0.605 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 16; `ORC-PDGZTALKSI.e5315f` |  |
| 2025 | eutectic: L \<-> λ + Ta3Fe2 | L: Ta 0.558; λ: Ta 0.434; Ta3Fe2: Ta 0.584 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 9; `ORC-PDGZTALKSI.eb8e7a` |  |
| 2023.15 | eutectic: Liq. ↔ μ + bcc |  | experimental | [1] Danon 2003; _cites Coelho 1995_ [doi](https://doi.org/10.1007/bf02664849) | Table 1, p. 5, row 9; `ORC-W5LKFIPFP5` |  |
| 2023 | eutectic: L \<-> β + μ |  | experimental | [3] Witusiewicz 2011; _cites Coelho 1995_ [doi](https://doi.org/10.1007/bf02664849) | Table 6, p. 14, row 11; `ORC-RRAOCGLQV2` |  |
| 2023 | eutectic: L -> μ + (Ta) |  | experimental | [2] Rajkumar 2015; _cites Coelho 1995_ [doi](https://doi.org/10.1007/bf02664849) | Table 2, p. 3, row 7; `ORC-WSBYHREGQG` |  |
| 2020.15 | eutectic: Liq. ↔ μ + bcc | μ: Ta 0.593; bcc: Ta 0.9362; L: Ta 0.6834 | model | [1] Danon 2003; _cites Coelho 1994_ | Table 1, p. 5, row 10; `ORC-COYBFCLV66` |  |
| 2020 | eutectic: L \<-> β + μ | L: Ta 0.683; β: Ta 0.936; μ: Ta 0.593 | model | [3] Witusiewicz 2011; _cites Coelho 1994_ | Table 6, p. 14, row 14; `ORC-HA5KCUILA7` |  |
| 2015 | eutectic: L -> μ + (Ta) | L: Ta 0.6503; μ: Ta 0.6153; (Ta): Ta 0.9223 | model | [2] Rajkumar 2015 | Table 2, p. 3, row 10; `ORC-VNMHXFVDRP` |  |
| 2000 | eutectic: L -> μ + (Ta) |  | experimental | [2] Rajkumar 2015 | Table 2, p. 3, row 9; `ORC-EWX4YQFYCD` |  |
| 1995.15 | eutectic: ε + μ ↔ Liq. | ε: Ta 0.366; μ: Ta 0.5384; L: Ta 0.42 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 5, row 13; `ORC-ZDXJ5LO4XL` |  |
| 1890.15 | eutectic: ε + μ ↔ Liq. |  | experimental | [1] Danon 2003; _cites Ichise 1989_ [doi](https://doi.org/10.2355/isijinternational.29.843) | Table 1, p. 5, row 15; `ORC-VUMRAXBWCT` |  |
| 1865.15 | eutectic: Liq. ↔ μ + bcc | μ: Ta 0.5384; bcc: Ta 0.95; L: Ta 0.6834 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 5, row 12; `ORC-KHZXCAL7PN` |  |
| 1865 | eutectic: L \<-> β + μ | L: Ta 0.683; β: Ta 0.959; μ: Ta 0.538 | model | [3] Witusiewicz 2011; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 6, p. 14, row 13; `ORC-HI4VTYW6LZ` |  |
| 1803.15 | eutectic: ε + μ ↔ Liq. |  | experimental | [1] Danon 2003; _cites Wetzig 1968_ [doi](https://doi.org/10.1002/pssb.19680270149) | Table 1, p. 5, row 16; `ORC-AEJO34DPYL` |  |
| 1726.15 | eutectic: Liq. ↔ ε + bcc(δ) | ε: Ta 0.272; L: Ta 0.0686 | model | [1] Danon 2003 | Table 1, p. 5, row 18; `ORC-GMCKSAVT2U` |  |
| 1726 | eutectic: L \<-> δ + λ | L: Ta 0.067; δ: Ta 0.042; λ: Ta 0.272 | model | [3] Witusiewicz 2011; _cites Danon 2003_ [doi](https://doi.org/10.1016/s0921-5093%2802%2900632-9) | Table 6, p. 14, row 22; `ORC-ITFAFKOVIF` |  |
| 1721 | eutectic: L -> (δFe) + ε | L: Ta 0.0629; (δFe): Ta 0.0228; ε: Ta 0.2983 | model | [2] Rajkumar 2015 | Table 2, p. 3, row 14; `ORC-V55HUT2ZEX` |  |
| 1716 | eutectic: L \<-> δ + λ | L: Ta 0.075; δ: Ta 0.021; λ: Ta 0.277 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 23; `ORC-2OJ4TNHSZZ.501f23` |  |
| 1716 | eutectic: L \<-> δ + λ | L: Ta 0.072; λ: Ta 0.277 | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 19; `ORC-2OJ4TNHSZZ.9edb36` |  |
| 1716 | eutectic: L -> (δFe) + ε | L: Ta 0.072; ε: Ta 0.277 | unspecified | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 2, p. 3, row 13; `ORC-DZOFVFQR4G` |  |
| 1715.15 | eutectic: Liq. ↔ ε + bcc(δ) | ε: Ta 0.2729; L: Ta 0.0797 | model | [1] Danon 2003; _cites Coelho 1994_ | Table 1, p. 5, row 17; `ORC-DMWBU57V63` |  |
| 1715 | eutectic: L \<-> δ + λ | L: Ta 0.08; δ: Ta 0.018; λ: Ta 0.273 | model | [3] Witusiewicz 2011; _cites Coelho 1994_ | Table 6, p. 14, row 21; `ORC-2XDNCZBRNN` |  |
| 1714.15 | eutectic: Liq. ↔ ε + bcc(δ) |  | experimental | [1] Danon 2003; _cites Ichise 1989_ [doi](https://doi.org/10.2355/isijinternational.29.843) | Table 1, p. 5, row 19; `ORC-AAP6HDWYXU` |  |
| 1714 | eutectic: L \<-> δ + λ |  | experimental | [3] Witusiewicz 2011; _cites Ichise 1989_ [doi](https://doi.org/10.2355/isijinternational.29.843) | Table 6, p. 14, row 17; `ORC-DU2WRRVHTY` |  |
| 1714 | eutectic: L -> (δFe) + ε |  | experimental | [2] Rajkumar 2015; _cites Ichise 1989_ [doi](https://doi.org/10.2355/isijinternational.29.843) | Table 2, p. 3, row 11; `ORC-FHTJGB2H4S` |  |
| 1713.15 | eutectic: Liq. ↔ ε + bcc(δ) | ε: Ta 0.333; L: Ta 0.079 | experimental | [1] Danon 2003; _cites Sinha 1967_ | Table 1, p. 5, row 20; `ORC-N5P73IXKHB` |  |
| 1713 | eutectic: L \<-> δ + λ | L: Ta 0.079; δ: Ta 0.028; λ: Ta 0.333 | experimental | [3] Witusiewicz 2011; _cites Sinha 1967_ | Table 6, p. 14, row 18; `ORC-2GPTOXBEZ7` |  |
| 1713 | eutectic: L -> (δFe) + ε | L: Ta 0.079; (δFe): Ta 0.028; ε: Ta 0.333 | experimental | [2] Rajkumar 2015; _cites Sinha 1967_ | Table 2, p. 3, row 12; `ORC-HNPYFSK6DW` |  |
| 1703.15 | eutectic: Liq. ↔ ε + bcc(δ) | ε: Ta 0.265; L: Ta 0.079 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 5, row 21; `ORC-52KU3KTDZF` |  |
| 1703 | eutectic: L \<-> δ + λ | L: Ta 0.079; δ: Ta 0.024; λ: Ta 0.265 | model | [3] Witusiewicz 2011; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 6, p. 14, row 20; `ORC-Z746A5HRZB` |  |
| 1648 | μ + (Ta) | μ: Ta 0.56; (Ta): Ta 0.947 | experimental | [2] Rajkumar 2015 | Table 5, p. 4, row 2; `ORC-6PFI32NWOF` |  |
| 1623 | μ + (Ta) | μ: Ta 0.553; (Ta): Ta 0.938 | experimental | [2] Rajkumar 2015 | Table 5, p. 4, row 1; `ORC-P3GIHAS462` |  |
| 1516 | (δFe) -> (γFe) + ε |  | unspecified | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 2, p. 3, row 18; `ORC-GYZ2MUXN5X` |  |
| 1516 | eutectoid: δ \<-> γ + λ |  | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 27; `ORC-OWGDLMMX52` |  |
| 1512.15 | eutectoid: bcc(δ) ↔ ε + γ | ε: Ta 0.3333; γ: Ta 0.005 | experimental | [1] Danon 2003; _cites Sinha 1967_ | Table 1, p. 5, row 22; `ORC-VMUVSWKJPY` |  |
| 1512 | eutectoid: δ \<-> γ + λ | δ: Ta 0.011; γ: Ta 0.005; λ: Ta 0.333 | experimental | [3] Witusiewicz 2011; _cites Sinha 1967_ | Table 6, p. 14, row 24; `ORC-M33CYEXGAO` |  |
| 1512 | (δFe) -> (γFe) + ε | (δFe): Ta 0.011; (γFe): Ta 0.005; ε: Ta 0.333 | experimental | [2] Rajkumar 2015; _cites Sinha 1967_ | Table 2, p. 3, row 15; `ORC-VTBX5QYTO4` |  |
| 1511 | eutectoid: δ \<-> γ + λ | δ: Ta 0.015; γ: Ta 0.011; λ: Ta 0.298 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 31; `ORC-YQE4JFMI7A` |  |
| 1504 | (δFe) -> (γFe) + ε | (δFe): Ta 0.0156; (γFe): Ta 0.00917; ε: Ta 0.3101 | model | [2] Rajkumar 2015 | Table 2, p. 3, row 19; `ORC-45LAZCV2TD` |  |
| 1501.15 | eutectoid: bcc(δ) ↔ ε + γ | ε: Ta 0.268; γ: Ta 0.0083 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 5, row 23; `ORC-NOFI7DDSIR` |  |
| 1501 | eutectoid: δ \<-> γ + λ | δ: Ta 0.013; γ: Ta 0.008; λ: Ta 0.268 | model | [3] Witusiewicz 2011; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 6, p. 14, row 28; `ORC-WWDUWRW24G` |  |
| 1493.15 | eutectoid: bcc(δ) ↔ ε + γ | ε: Ta 0.27; γ: Ta 0.01 | model | [1] Danon 2003 | Table 1, p. 5, row 25; `ORC-CXAKQQ5L4S` |  |
| 1493.15 | eutectoid: bcc(δ) ↔ ε + γ | ε: Ta 0.0333; γ: Ta 0.0096 | experimental | [1] Danon 2003; _cites Genders 1936_ | Table 1, p. 5, row 24; `ORC-P5T4F6354Z` |  |
| 1493 | eutectoid: δ \<-> γ + λ | δ: Ta 0.015; γ: Ta 0.01; λ: Ta 0.27 | model | [3] Witusiewicz 2011; _cites Danon 2003_ [doi](https://doi.org/10.1016/s0921-5093%2802%2900632-9) | Table 6, p. 14, row 30; `ORC-7VXCYSMSSP` |  |
| 1493 | eutectoid: δ \<-> γ + λ | δ: Ta 0.015; γ: Ta 0.01; λ: Ta 0.333 | experimental | [3] Witusiewicz 2011; _cites Genders 1936_ | Table 6, p. 14, row 25; `ORC-DQMHPITELC` |  |
| 1493 | (δFe) -> (γFe) + ε | (δFe): Ta 0.015; (γFe): Ta 0.01; ε: Ta 0.333 | experimental | [2] Rajkumar 2015; _cites Genders 1936_ | Table 2, p. 3, row 16; `ORC-VUPRFQ23TZ` |  |
| 1489.15 | eutectoid: bcc(δ) ↔ ε + γ | ε: Ta 0.2899; γ: Ta 0.0081 | model | [1] Danon 2003; _cites Coelho 1994_ | Table 1, p. 5, row 26; `ORC-2ZCSUBHNH5` |  |
| 1489 | eutectoid: δ \<-> γ + λ | δ: Ta 0.013; γ: Ta 0.008; λ: Ta 0.29 | model | [3] Witusiewicz 2011; _cites Coelho 1994_ | Table 6, p. 14, row 29; `ORC-DTUDYZ6CB6` |  |
| 1488.15 | eutectoid: bcc(δ) ↔ ε + γ | ε: Ta 0.3333; γ: Ta 0.0086 | experimental | [1] Danon 2003; _cites Fischer 1970_ [doi](https://doi.org/10.1002/srin.197001633) | Table 1, p. 5, row 27; `ORC-M6MWMITJJR` |  |
| 1488 | (δFe) -> (γFe) + ε | (δFe): Ta 0.014; (γFe): Ta 0.009; ε: Ta 0.333 | experimental | [2] Rajkumar 2015; _cites Fischer 1970_ [doi](https://doi.org/10.1002/srin.197001633) | Table 2, p. 3, row 17; `ORC-BACNHOSW5O` |  |
| 1488 | eutectoid: δ \<-> γ + λ | δ: Ta 0.014; γ: Ta 0.009; λ: Ta 0.333 | experimental | [3] Witusiewicz 2011; _cites Fischer 1970_ [doi](https://doi.org/10.1002/srin.197001633) | Table 6, p. 14, row 26; `ORC-JYCJPJWQGC` |  |
| 1250.15 | peritectoid: bcc(α) ↔ γ + ε | γ: Ta 0.0043; ε: Ta 0.3082 | model | [1] Danon 2003; _cites Coelho 1994_ | Table 1, p. 5, row 28; `ORC-NJ3QSZITRP` |  |
| 1250 | peritectoid: γ + λ \<-> α | γ: Ta 0.004; λ: Ta 0.308; α: Ta 0.008 | model | [3] Witusiewicz 2011; _cites Coelho 1994_ | Table 6, p. 14, row 37; `ORC-LF5KWX7GAR` |  |
| 1247.15 | α + γ + ε | α: Ta 0.0032; γ: Ta 0.002; ε: Ta 0.3333 | experimental | [1] Danon 2003; _cites Genders 1936_ | Table 1, p. 6, row 2; `ORC-7NZ2LTXUIS` |  |
| 1247 | peritectoid: γ + λ \<-> α | γ: Ta 0.002; λ: Ta 0.333; α: Ta 0.003 | experimental | [3] Witusiewicz 2011; _cites Genders 1936_ | Table 6, p. 14, row 34; `ORC-2TDBFYMT7V` |  |
| 1247 | (γFe) + ε -> (αFe) | (γFe): Ta 0.002; ε: Ta 0.333; (αFe): Ta 0.003 | experimental | [2] Rajkumar 2015; _cites Genders 1936_ | Table 2, p. 3, row 22; `ORC-IJFCPAUX4U` |  |
| 1246 | peritectoid: γ + λ \<-> α | α: Ta 0.006 | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 35; `ORC-J2HGJQOSAI` |  |
| 1246 | (γFe) + ε -> (αFe) | (αFe): Ta 0.006 | unspecified | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 2, p. 3, row 23; `ORC-PXARXN4HG2` |  |
| 1245.15 | peritectoid: bcc(α) ↔ γ + ε | γ: Ta 0.003; ε: Ta 0.3333 | experimental | [1] Danon 2003; _cites Sinha 1967_ | Table 1, p. 5, row 29; `ORC-RXT4SAPPUQ` |  |
| 1245 | peritectoid: γ + λ \<-> α | γ: Ta 0.003; λ: Ta 0.333; α: Ta 0.006 | experimental | [3] Witusiewicz 2011; _cites Sinha 1967_ | Table 6, p. 14, row 32; `ORC-K2UZ43CFCY` |  |
| 1245 | (γFe) + ε -> (αFe) | (γFe): Ta 0.003; ε: Ta 0.333; (αFe): Ta 0.006 | experimental | [2] Rajkumar 2015; _cites Sinha 1967_ | Table 2, p. 3, row 20; `ORC-NQ6WPYCR7E` |  |
| 1245 | (γFe) + ε -> (αFe) | (γFe): Ta 0.00392; ε: Ta 0.3218; (αFe): Ta 0.00836 | model | [2] Rajkumar 2015 | Table 2, p. 3, row 24; `ORC-P7NA6TFUWU` |  |
| 1242 | peritectoid: γ + λ \<-> α | γ: Ta 0.004; λ: Ta 0.319; α: Ta 0.008 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 39; `ORC-YR5OSEUWWI` |  |
| 1238.15 | α + γ + ε | α: Ta 0.0071; γ: Ta 0.004; ε: Ta 0.3333 | experimental | [1] Danon 2003; _cites Fischer 1970_ [doi](https://doi.org/10.1002/srin.197001633) | Table 1, p. 6, row 1; `ORC-7R5JK2WKMG` |  |
| 1238 | (γFe) + ε -> (αFe) | (γFe): Ta 0.004; ε: Ta 0.333; (αFe): Ta 0.007 | experimental | [2] Rajkumar 2015; _cites Fischer 1970_ [doi](https://doi.org/10.1002/srin.197001633) | Table 2, p. 3, row 21; `ORC-UNASOYRSGQ` |  |
| 1238 | peritectoid: γ + λ \<-> α | γ: Ta 0.004; λ: Ta 0.333; α: Ta 0.007 | experimental | [3] Witusiewicz 2011; _cites Fischer 1970_ [doi](https://doi.org/10.1002/srin.197001633) | Table 6, p. 14, row 33; `ORC-VU7DY2KXVJ` |  |
| 1220.15 | α + γ + ε | α: Ta 0.0046; γ: Ta 0.002; ε: Ta 0.276 | model | [1] Danon 2003; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 1, p. 6, row 3; `ORC-RJ5SE7RMUK` |  |
| 1220 | peritectoid: γ + λ \<-> α | γ: Ta 0.002; λ: Ta 0.276; α: Ta 0.005 | model | [3] Witusiewicz 2011; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 6, p. 14, row 36; `ORC-TFQCBGCDU6` |  |
| 1199.15 | α + γ + ε | α: Ta 0.0022; γ: Ta 0.001; ε: Ta 0.2786 | model | [1] Danon 2003 | Table 1, p. 6, row 4; `ORC-PVXVMEM7AH` |  |
| 1199 | peritectoid: γ + λ \<-> α | γ: Ta 0.001; λ: Ta 0.279; α: Ta 0.002 | model | [3] Witusiewicz 2011; _cites Danon 2003_ [doi](https://doi.org/10.1016/s0921-5093%2802%2900632-9) | Table 6, p. 14, row 38; `ORC-6OJMMXDGA4` |  |
| 1043 | other: α(pm) \<-> α(fm), λ | α(pm): Ta 4.000e-4; α(fm): Ta 4.000e-4; λ: Ta 0.285 | model | [3] Witusiewicz 2011; _cites Danon 2003_ [doi](https://doi.org/10.1016/s0921-5093%2802%2900632-9) | Table 6, p. 14, row 40; `ORC-SODIHEOALD` |  |
| 1041 | other: α(pm) \<-> α(fm), λ |  | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 41; `ORC-T5NBQPCGID.b66c02` |  |
| 1041 | other: α(pm) \<-> α(fm), λ | α(pm): Ta 0.004; α(fm): Ta 0.004; λ: Ta 0.328 | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 42; `ORC-T5NBQPCGID.c1e2f9` |  |

## 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, Fe–Ta system (25)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| Fe0.359Ta0.641 |  | -5.8 kJ/mol (basis unstated) ± 2.1 | 298.15 | experimental |  |  | [3] Witusiewicz 2011 | Table 4, p. 10, row 7; `ORC-RBIUGBH6AP.8a53fd` |  |
| Fe0.477Ta0.523 |  | -7.1 kJ/mol (basis unstated) ± 1.4 | 298.15 | experimental |  |  | [3] Witusiewicz 2011 | Table 4, p. 10, row 6; `ORC-QZSSUKPVHP.3aa425` |  |
| Fe0.638Ta0.362 |  | -5.4 kJ/mol (basis unstated) ± 1.5 | 298.15 | experimental |  |  | [3] Witusiewicz 2011 | Table 4, p. 10, row 5; `ORC-ZX3SPCCEO7.728de2` |  |
| Fe0.678Ta0.322 |  | -5.7 kJ/mol (basis unstated) ± 1.8 | 298.15 | experimental |  |  | [3] Witusiewicz 2011 | Table 4, p. 10, row 4; `ORC-MNHCCD4UUO.f203e2` |  |
| Fe0.844Ta0.156 |  | -2.6 kJ/mol (basis unstated) ± 1.9 | 298.15 | experimental |  |  | [3] Witusiewicz 2011 | Table 4, p. 10, row 3; `ORC-L7LSQ45SMI.dc48ed` |  |
| Fe1Ta12 |  | 6.15538 kJ/mol-atom | 0 | DFT |  |  | [2] Rajkumar 2015 | Table 9, p. 6, row 7; `ORC-A23QJB2WN2` |  |
| Fe2Ta11 |  | 28.3285 kJ/mol-atom | 0 | DFT |  |  | [2] Rajkumar 2015 | Table 9, p. 6, row 6; `ORC-U24HI3NZA2` |  |
| Fe3Ta10 |  | 31.9038 kJ/mol-atom | 0 | DFT |  |  | [2] Rajkumar 2015 | Table 9, p. 6, row 5; `ORC-HZPR4ESTX6` |  |
| Fe8Ta5 |  | -8.73 kJ/mol-atom | 0 | DFT |  |  | [2] Rajkumar 2015 | Table 9, p. 6, row 4; `ORC-TDPDNRKB6I` |  |
| Fe9Ta4 |  | -6.68769 kJ/mol-atom | 0 | DFT |  |  | [2] Rajkumar 2015 | Table 9, p. 6, row 3; `ORC-ADB5HMRQKR` |  |
| Laves phase (ε) |  | -20.118 kJ/mol (basis unstated) |  | unspecified |  |  | [2] Rajkumar 2015 | Table 7, p. 6, row 8; `ORC-4MPWNMO3I6.ef214c` |  |
| Laves phase (ε) |  | -19.99 kJ/mol (basis unstated) |  | model |  |  | [2] Rajkumar 2015; _cites De 1988_ | Table 7, p. 6, row 6; `ORC-NUR7WPTFLH.bdd694` |  |
| Laves phase (ε) |  | -19.767 kJ/mol (basis unstated) |  | unspecified |  |  | [2] Rajkumar 2015 | Table 7, p. 6, row 7; `ORC-5LLSIM5UCG.de2630` |  |
| Laves phase (ε) |  | -19.25 kJ/mol (basis unstated) |  | model |  |  | [2] Rajkumar 2015; _cites Gerassimov 1972_ | Table 7, p. 6, row 5; `ORC-22PSFQMIOF.6bcffd` |  |
| Laves phase (ε) |  | -18.61 kJ/mol (basis unstated) |  | DFT |  |  | [2] Rajkumar 2015; _cites Pavlu 2012_ [doi](https://doi.org/10.2298/jmmb120704050p) | Table 7, p. 6, row 4; `ORC-H62EXIM4U3.3bbcfd` |  |
| Laves phase (ε) |  | -6.3 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [2] Rajkumar 2015; _cites Meschel 2006_ [doi](https://doi.org/10.1016/j.jallcom.2005.08.006) | Table 7, p. 6, row 3; `ORC-IPOAKGUJGN.6cbdce` |  |
| Laves phase (ε) |  | -5.7 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 7, p. 6, row 1; `ORC-K2NGAHX5LS.b45d5b` |  |
| Laves phase (ε) |  | -5.4 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 7, p. 6, row 2; `ORC-477HHICSHE.c1f08a` |  |
| Mu phase (μ) |  | -22.586 kJ/mol (basis unstated) |  | model |  |  | [2] Rajkumar 2015; _cites De 1988_ | Table 7, p. 6, row 11; `ORC-D7WZOTONHT.6fa33b` |  |
| Mu phase (μ) |  | -20.529 kJ/mol (basis unstated) |  | unspecified |  |  | [2] Rajkumar 2015 | Table 7, p. 6, row 14; `ORC-NKZELQI6OH.f445a5` |  |
| Mu phase (μ) |  | -19.868 kJ/mol (basis unstated) |  | unspecified |  |  | [2] Rajkumar 2015 | Table 7, p. 6, row 12; `ORC-LS5LDTB7GZ.ba7f16` |  |
| Mu phase (μ) |  | -17.684 kJ/mol (basis unstated) |  | unspecified |  |  | [2] Rajkumar 2015 | Table 7, p. 6, row 13; `ORC-NRAWP2EVQL.cdfee1` |  |
| Mu phase (μ) |  | -17.224 kJ/mol (basis unstated) |  | unspecified |  |  | [2] Rajkumar 2015 | Table 7, p. 6, row 15; `ORC-BL47JDRG7E.96fbc6` |  |
| Mu phase (μ) |  | -7.1 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 7, p. 6, row 9; `ORC-G6362S44CE.011d0d` |  |
| Mu phase (μ) |  | -5.8 kJ/mol (basis unstated) | 298.15 | experimental |  |  | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 7, p. 6, row 10; `ORC-27BAMP5NST.2ef24b` |  |

## Other properties

### Phase transition (71)

Table: Phase transition, Fe–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 1041 K | 1041 | α(pm) ↔ α(fm), λ; _alloy: Fe 0.844, Ta 0.156_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 19; `ORC-DVMNE6WLXE` |  |
| Phase transition | 1041 K | 1041 | α(pm) ↔ α(fm), λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 18; `ORC-SOT2VHKBVC` |  |
| Phase transition | 1043 K | 1043 | α(pm) ↔ α(fm), λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 17; `ORC-QKU4EWDHVC` |  |
| Phase transition | 1241 K | 1241 | λ + γ ↔ α (pm); _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 14; `ORC-A3UAPJXNY2` |  |
| Phase transition | 1242 K | 1242 | λ + γ ↔ α (pm); _alloy: Fe 0.844, Ta 0.156_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 16; `ORC-P4QBGYU3IS` |  |
| Phase transition | 1251 K | 1251 | λ + γ ↔ α (pm); _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 15; `ORC-GNGXS4F7MB` |  |
| Phase transition | 1511 K | 1511 | δ ↔ λ + γ; _alloy: Fe 0.844, Ta 0.156_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 13; `ORC-ORYERE34QF` |  |
| Phase transition | 1513 K | 1513 | δ ↔ λ + γ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 11; `ORC-QS6Q4DCMYH` |  |
| Phase transition | 1520 K | 1520 | δ ↔ λ + γ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 12; `ORC-XKYIZPTMPT` |  |
| Phase transition | 1685 K | 1685 | L ↔ δ + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 7; `ORC-NUVE63BVGO` |  |
| Phase transition | 1704 K | 1704 | L ↔ δ + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 9; `ORC-JNNRRYEJNQ` |  |
| Phase transition | 1716 K | 1716 | L ↔ δ + λ; _alloy: Fe 0.844, Ta 0.156_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 10; `ORC-P5GPTUMJEN` |  |
| Phase transition | 1719 K | 1719 | L ↔ δ + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 6; `ORC-2ZM52N3OZG` |  |
| Phase transition | 1724 K | 1724 | L ↔ δ + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 8; `ORC-M522JVE5GD` |  |
| Phase transition | 1945 K | 1945 | L/L + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 4; `ORC-BLTDVVMRYS` |  |
| Phase transition | 1950 K | 1950 | L/L + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 2; `ORC-Y3TD24U6BL` |  |
| Phase transition | 1959 K | 1959 | L/L + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 3; `ORC-GZNOW2O7BR` |  |
| Phase transition | 1959 K | 1959 | L/L + λ; _alloy: Fe 0.844, Ta 0.156_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 5; `ORC-KSO6UJKIEL` |  |
| Phase transition | 1960 K | 1960 | L/L + λ; _alloy: Fe 0.844, Ta 0.156_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 1; `ORC-JU5QBFARU2` |  |
| Phase transition | 1966 K | 1966 | L + μ/μ; _alloy: Fe 0.438, Ta 0.562_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 54; `ORC-YU5REMY3Z7` |  |
| Phase transition | 2000 K | 2000 | L ⇌ μ + (Ta) | experimental | [2] Rajkumar 2015 | p. 3; `ORC-F4YFV3PDIL` | “In addition to the spike corresponding to the liquidus, Fe70.8 at% Ta and Fe-87.2 at% Ta alloys show another spike (Fig. 2a, b) in their cooling curves around ∼2000 K, which corresponds to the invariant L ⇌ μ + (Ta).” |
| Phase transition | 2025 K | 2025 | L ↔ β + μ; _alloy: Fe 0.358, Ta 0.642_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 63; `ORC-ZAO5ONZTWG` |  |
| Phase transition | 2028 K | 2028 | L/L + μ; _alloy: Fe 0.438, Ta 0.562_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 51; `ORC-N32OBHACLG` |  |
| Phase transition | 2029 K | 2029 | L/L + μ; _alloy: Fe 0.358, Ta 0.642_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 60; `ORC-Y6ZS5LGP5V` |  |
| Phase transition | 2030 K | 2030 | L ↔ β + μ; _alloy: Fe 0.358, Ta 0.642_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 61; `ORC-7A3KODY4S5` |  |
| Phase transition | 2030 K | 2030 | congruent melting: L \<-> Ta3Fe2; _L: Ta 0.605; Ta3Fe2: Ta 0.605_ | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 8; `ORC-BXV6B4VSOP` |  |
| Phase transition | 2035 K | 2035 | congruent melting: L \<-> λ; _L: Ta 0.339; λ: Ta 0.33_ | model | [3] Witusiewicz 2011; _cites Srikanth 1994_ [doi](https://doi.org/10.1016/0925-8388%2894%2990747-1) | Table 6, p. 14, row 2; `ORC-2YHYJOKKXS` |  |
| Phase transition | 2037 K | 2037 | L/L + μ; _alloy: Fe 0.358, Ta 0.642_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 56; `ORC-MHU2KUIIGM` |  |
| Phase transition | 2038 K | 2038 | L/L + μ; _alloy: Fe 0.358, Ta 0.642_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 57; `ORC-F7FGHIMI26` |  |
| Phase transition | 2041 K | 2041 | L + μ/μ; _alloy: Fe 0.438, Ta 0.562_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 55; `ORC-TEDYNJJTXO` |  |
| Phase transition | 2041 K | 2041 | L ↔ β + μ; _alloy: Fe 0.358, Ta 0.642_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 62; `ORC-DBLWWEXJ5O` |  |
| Phase transition | 2042 K | 2042 | L/L + μ; _alloy: Fe 0.358, Ta 0.642_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 59; `ORC-CZQ47JKIUA` |  |
| Phase transition | 2047 K | 2047 | congruent melting: L \<-> λ; _L: Ta 0.386; λ: Ta 0.386_ | model | [3] Witusiewicz 2011; _cites Danon 2003_ [doi](https://doi.org/10.1016/s0921-5093%2802%2900632-9) | Table 6, p. 14, row 3; `ORC-CZ73K2XM36` |  |
| Phase transition | 2048 K | 2048 | L + μ/μ; _alloy: Fe 0.476, Ta 0.524_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 49; `ORC-ZTIORVRFUQ` |  |
| Phase transition | 2048 K | 2048 | L -> ε; _L: Ta 0.326; ε: Ta 0.326_ | experimental | [2] Rajkumar 2015; _cites Elliott 1958_ | Table 2, p. 3, row 1; `ORC-7P3CTG46LB` |  |
| Phase transition | 2048 K | 2048 | congruent melting: L \<-> λ; _L: Ta 0.326; λ: Ta 0.326_ | experimental | [3] Witusiewicz 2011; _cites Elliot 1958_ | Table 6, p. 14, row 1; `ORC-SBE3FUO55Y` |  |
| Phase transition | 2055 K | 2055 | L + λ ↔ μ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 40; `ORC-TDB22IVHIQ` |  |
| Phase transition | 2055 K | 2055 | L/L + μ; _alloy: Fe 0.438, Ta 0.562_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 52; `ORC-UVQA2SFUL4` |  |
| Phase transition | 2057 K | 2057 | L + μ/μ; _alloy: Fe 0.476, Ta 0.524_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 50; `ORC-FHSRAQ2XQQ` |  |
| Phase transition | 2057 K | 2057 | L/L + μ; _alloy: Fe 0.358, Ta 0.642_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 58; `ORC-GBRX6XCSY5` |  |
| Phase transition | 2058 K | 2058 | L + μ/μ; _alloy: Fe 0.476, Ta 0.524_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 48; `ORC-T3KH7X3L6H` |  |
| Phase transition | 2058 K | 2058 | L/L + μ; _alloy: Fe 0.476, Ta 0.524_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 46; `ORC-3Y45VNSUST` |  |
| Phase transition | 2058 K | 2058 | L/L + μ; _alloy: Fe 0.476, Ta 0.524_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 45; `ORC-5LORW3IGQJ` |  |
| Phase transition | 2059 K | 2059 | L + μ/μ; _alloy: Fe 0.438, Ta 0.562_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 53; `ORC-55RPUH5V2G` |  |
| Phase transition | 2060 K | 2060 | L + λ ↔ μ; _alloy: Fe 0.549, Ta 0.451_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 43; `ORC-DFZSC5JXA3` |  |
| Phase transition | 2060 K | 2060 | L + λ ↔ μ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 39; `ORC-IHWE6R3WSO` |  |
| Phase transition | 2060 K | 2060 | L/L + μ; _alloy: Fe 0.476, Ta 0.524_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 47; `ORC-GTEY3NECPN` |  |
| Phase transition | 2061 K | 2061 | L + λ ↔ μ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 41; `ORC-CY7CE2RJAU` |  |
| Phase transition | 2065 K | 2065 | L/L + μ; _alloy: Fe 0.476, Ta 0.524_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 44; `ORC-AJVQ3BP75H` |  |
| Phase transition | 2068 K | 2068 | L + λ ↔ μ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 42; `ORC-UTYYEHSQRP` |  |
| Phase transition | 2088 K | 2088 | L + λ/λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 26; `ORC-DDBFSYH2XH` |  |
| Phase transition | 2088 K | 2088 | L + λ/λ; _alloy: Fe 0.678, Ta 0.322_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 28; `ORC-LKFJQHEWHI` |  |
| Phase transition | 2088 K | 2088 | L + λ/λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 27; `ORC-WYJN6PVROL` |  |
| Phase transition | 2090 K | 2090 | L/L + λ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 34; `ORC-UNLJRUQOW2` |  |
| Phase transition | 2094 K | 2094 | L/L + λ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 37; `ORC-3JMKOHZKBZ` |  |
| Phase transition | 2102 K | 2102 | L/L + λ; _alloy: Fe 0.549, Ta 0.451_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 38; `ORC-H2TI6GZJCH` |  |
| Phase transition | 2103 K | 2103 | L + λ/λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 24; `ORC-FVYYHCFQUA` |  |
| Phase transition | 2116 K | 2116 | L + λ/λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 25; `ORC-D4YHPCCP23` |  |
| Phase transition | 2116 K | 2116 | L/L + λ; _alloy: Fe 0.549, Ta 0.451_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 36; `ORC-WZFRY42PXE` |  |
| Phase transition | 2120 K | 2120 | L/L + λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 21; `ORC-AU462XIFEJ` |  |
| Phase transition | 2126 K | 2126 | λ/L + λ; _alloy: Fe 0.638, Ta 0.362_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 33; `ORC-VT73ADQIXD` |  |
| Phase transition | 2129 K | 2129 | L/L + λ; _alloy: Fe 0.678, Ta 0.322_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 23; `ORC-XC2MGGLYWV` |  |
| Phase transition | 2131 K | 2131 | L/L + λ; _alloy: Fe 0.638, Ta 0.362_ | model | [3] Witusiewicz 2011 | Table 3, p. 8, row 31; `ORC-G4N5T4U2E2` |  |
| Phase transition | 2131 K | 2131 | congruent melting: L \<-> λ; _L: Ta 0.35; λ: Ta 0.35_ | model | [3] Witusiewicz 2011 | Table 6, p. 14, row 5; `ORC-POZJCSZOA4` |  |
| Phase transition | 2136 K | 2136 | L -> ε; _L: Ta 0.348; ε: Ta 0.348_ | unspecified | [2] Rajkumar 2015; _cites Witusiewicz 2011_ [doi](https://doi.org/10.1016/j.intermet.2011.03.018) | Table 2, p. 3, row 3; `ORC-Z36IG5LOVB` |  |
| Phase transition | 2136 K | 2136 | L/L + λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 22; `ORC-EE3YTHXQZI` |  |
| Phase transition | 2136 K | 2136 | congruent melting: L \<-> λ; _L: Ta 0.348; λ: Ta 0.348_ | experimental | [3] Witusiewicz 2011 | Table 6, p. 14, row 4; `ORC-Z26CYZ62WB` |  |
| Phase transition | 2136 K | 2136 | λ/L + λ; _alloy: Fe 0.638, Ta 0.362_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 32; `ORC-WKR7IZFYRY` |  |
| Phase transition | 2137 K | 2137 | L -> ε; _L: Ta 0.3598; ε: Ta 0.3598_ | model | [2] Rajkumar 2015 | Table 2, p. 3, row 4; `ORC-GD3Y7EZASF` |  |
| Phase transition | 2137 K | 2137 | L/L + λ; _alloy: Fe 0.678, Ta 0.322_ | experimental | [3] Witusiewicz 2011 | Table 3, p. 8, row 20; `ORC-2TLAGVARTO` |  |
| Phase transition | 2152 K | 2152 | L -> ε; _L: Ta 0.334; ε: Ta 0.334_ | experimental | [2] Rajkumar 2015; _cites Keitz 1998_ | Table 2, p. 3, row 2; `ORC-4V5M3EKHM6` |  |

### Phase equilibrium (13)

Table: Phase equilibrium, Fe–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase assemblage |  |  | λ; _alloy: Fe 0.638, Ta 0.362_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 13; `ORC-5ANYQIO7O6` |  |
| Phase assemblage |  |  | λ + (αFe); _alloy: Fe 0.85, Ta 0.15_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 1; `ORC-CGCSSSHLSZ` |  |
| Phase assemblage |  |  | λ + (αFe)b; _alloy: Fe 0.68, Ta 0.32_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 3; `ORC-2NG2CHY4OT` |  |
| Phase assemblage |  |  | μ + Ta3Fe2b; _alloy: Fe 0.48, Ta 0.52_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 9; `ORC-3J7SSZ5XCM` |  |
| Phase assemblage |  |  | μ + β; _alloy: Fe 0.36, Ta 0.64_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 11; `ORC-SWBSZCRXZI` |  |
| Phase assemblage |  |  | μ + λ + Ta3Fe2b; _alloy: Fe 0.55, Ta 0.45_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 7; `ORC-FGEC6OWN6S` |  |
| Phase assemblage |  | 1673 | λ + (αFe); _alloy: Fe 0.85, Ta 0.15_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 2; `ORC-7AVQ72NEZP` |  |
| Phase assemblage |  | 1973 | λ; _alloy: Fe 0.68, Ta 0.32_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 4; `ORC-W4BGLSZN7I` |  |
| Phase assemblage |  | 1973 | μ + Ta3Fe2b; _alloy: Fe 0.48, Ta 0.52_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 8; `ORC-7G56EZXI35` |  |
| Phase assemblage |  | 1973 | μ + Ta3Fe2b; _alloy: Fe 0.44, Ta 0.56_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 10; `ORC-HNRQ7P4N67` |  |
| Phase assemblage |  | 1973 | μ + β; _alloy: Fe 0.36, Ta 0.64_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 12; `ORC-VSWFH3RF72` |  |
| Phase assemblage |  | 2073 | λ; _alloy: Fe 0.638, Ta 0.362_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 5; `ORC-AHNIKUXM3T` |  |
| Phase assemblage |  | 2073 | μ + λ + Ta3Fe2b; _alloy: Fe 0.55, Ta 0.45_ | experimental | [3] Witusiewicz 2011 | Table 2, p. 2, row 6; `ORC-G6RGMYHFNP` |  |

### Formation (11)

Table: Formation, Fe–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Gibbs energy of formation; _printed: ΔfG°_ | -19.793 kJ/mol (basis unstated) | 1070 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | model | [2] Rajkumar 2015 | Table 11, p. 8, row 2; `ORC-7OKKG73ZOI` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -19.628 kJ/mol (basis unstated) | 1070 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | experimental | [2] Rajkumar 2015; _cites Barbi 1970_ [doi](https://doi.org/10.1016/0022-5088%2870%2990137-2) | Table 11, p. 8, row 1; `ORC-YGRPRGM55Q` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -19.458 kJ/mol (basis unstated) | 1185 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | experimental | [2] Rajkumar 2015; _cites Barbi 1970_ [doi](https://doi.org/10.1016/0022-5088%2870%2990137-2) | Table 11, p. 8, row 3; `ORC-U4ZG2FH5UA` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -19.384 kJ/mol (basis unstated) | 1185 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | model | [2] Rajkumar 2015 | Table 11, p. 8, row 4; `ORC-ZFRXTDDMLE` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -19.06 kJ/mol (basis unstated) | 1260 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | model | [2] Rajkumar 2015 | Table 11, p. 8, row 8; `ORC-6RZYF43OYY` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -22.381 kJ/mol (basis unstated) | 1260 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | experimental | [2] Rajkumar 2015; _cites Rezukhina 1973_ | Table 11, p. 8, row 7; `ORC-APV5EAWVG4` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -22.299 kJ/mol (basis unstated) | 1300 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | experimental | [2] Rajkumar 2015; _cites Rezukhina 1973_ | Table 11, p. 8, row 9; `ORC-M62KKQ2P77` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -19.287 kJ/mol (basis unstated) | 1300 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | experimental | [2] Rajkumar 2015; _cites Barbi 1970_ [doi](https://doi.org/10.1016/0022-5088%2870%2990137-2) | Table 11, p. 8, row 5; `ORC-OVX4AXEPBO` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -18.891 kJ/mol (basis unstated) | 1300 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | model | [2] Rajkumar 2015 | Table 11, p. 8, row 6; `ORC-PZLWLXW26I` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -18.725 kJ/mol (basis unstated) | 1340 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | model | [2] Rajkumar 2015 | Table 11, p. 8, row 12; `ORC-AXOGKVHNWI` |  |
| Gibbs energy of formation; _printed: ΔfG°_ | -22.217 kJ/mol (basis unstated) | 1340 | ε; _alloy: Fe 0.6667, Ta 0.3333_ | experimental | [2] Rajkumar 2015; _cites Rezukhina 1973_ | Table 11, p. 8, row 11; `ORC-MIMWTC5A6Z` |  |

### Crystal structure (27)

Table: Crystal structure, Fe–Ta system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Lattice a | 2.8665 Å | 298.15 | α, (αFe); _alloy: Ta 0_ | model | [3] Witusiewicz 2011; _cites Massalski 1990_ | Table 1, p. 2, row 1; `ORC-XVVADKNXGP` |  |
| Lattice a | 4.816 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Kuo 1953_ [doi](https://doi.org/10.1016/0001-6160%2853%2990031-5) | Table 1, p. 2, row 7; `ORC-A6QRQXK77C.df7f29` |  |
| Lattice a | 4.8 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Wallbaum 1941_ | Table 1, p. 2, row 6; `ORC-B4L3X3P5Z7.ac60fc` |  |
| Lattice a | 4.8 Å | 298.15 | λ, ε, TaFe2; _alloy: Ta 0.333333_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 9; `ORC-K2ASB577SG.93dfe0` |  |
| Lattice a | 4.81 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Jellinghaus 1935_ [doi](https://doi.org/10.1002/zaac.19352230405) | Table 1, p. 2, row 5; `ORC-L6LMBT75QQ.232bfa` |  |
| Lattice a | 4.806 Å | 298.15 | λ, ε, TaFe2; _alloy: Ta 0.333333_ | experimental | [3] Witusiewicz 2011; _cites Jones 1972_ [doi](https://doi.org/10.1007/bf02644249) | Table 1, p. 2, row 11; `ORC-M4S3MHU2JB.9bea2f` |  |
| Lattice a | 4.86 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 10; `ORC-OC7LM6LMQC.552606` |  |
| Lattice a | 4.817 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Elliot 1958_ | Table 1, p. 2, row 8; `ORC-V5WO5E3ST3.9311cb` |  |
| Lattice a | 4.827 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.666, Ta 0.334; λ, ε, TaFe2: Fe 0.666, Ta 0.334_ | unspecified | [3] Witusiewicz 2011; _cites von Keitz A 1998_ | Table 1, p. 2, row 12; `ORC-VTLJZUX2YR.ec76c0` |  |
| Lattice a | 4.911 Å | 298.15 | μ, TaFe, Ta6Fe7; _μ: Fe 0.51, Ta 0.49; μ, TaFe, Ta6Fe7: Fe 0.51, Ta 0.49_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 13; `ORC-2QZQGKG5L7.c947ab` |  |
| Lattice a | 4.95 Å | 298.15 | μ, TaFe, Ta6Fe7; _μ: Fe 0.46, Ta 0.54; μ, TaFe, Ta6Fe7: Fe 0.46, Ta 0.54_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 14; `ORC-44CLVSHKPS.d15dff` |  |
| Lattice a | 4.919 Å | 298.15 | μ, TaFe, Ta6Fe7; _μ: Fe 0.5, Ta 0.5; μ, TaFe, Ta6Fe7: Fe 0.5, Ta 0.5_ | experimental | [3] Witusiewicz 2011; _cites Kripyakevich 1968_ | Table 1, p. 2, row 15; `ORC-OQNMASIGUT.0f7549` |  |
| Lattice a | 8.3 Å | 1073.15 | UNKNOWN; _alloy: Fe 0.35, Ta 0.65_ | experimental | [3] Witusiewicz 2011; _cites Lin 1999_ [doi](https://doi.org/10.1016/s0925-8388%2899%2900138-3) | Table 1, p. 2, row 16; `ORC-RHUJ3PJKBU.0fc640` |  |
| Lattice a | 3.6467 Å | 1188.15 | γ, (γFe); _alloy: Ta 0_ | model | [3] Witusiewicz 2011; _cites Massalski 1990_ | Table 1, p. 2, row 4; `ORC-RNXZMRVAKO` |  |
| Lattice a | 2.9315 Å | 1753.15 | δ, (δFe); _alloy: Ta 0_ | model | [3] Witusiewicz 2011; _cites Massalski 1990_ | Table 1, p. 2, row 2; `ORC-QAPWCMUQ37` |  |
| Lattice c | 7.868 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Kuo 1953_ [doi](https://doi.org/10.1016/0001-6160%2853%2990031-5) | Table 1, p. 2, row 7; `ORC-A6QRQXK77C.303d79` |  |
| Lattice c | 7.84 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Wallbaum 1941_ | Table 1, p. 2, row 6; `ORC-B4L3X3P5Z7.a14bdc` |  |
| Lattice c | 7.84 Å | 298.15 | λ, ε, TaFe2; _alloy: Ta 0.333333_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 9; `ORC-K2ASB577SG.73832c` |  |
| Lattice c | 7.888 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Jellinghaus 1935_ [doi](https://doi.org/10.1002/zaac.19352230405) | Table 1, p. 2, row 5; `ORC-L6LMBT75QQ.b082fe` |  |
| Lattice c | 7.846 Å | 298.15 | λ, ε, TaFe2; _alloy: Ta 0.333333_ | experimental | [3] Witusiewicz 2011; _cites Jones 1972_ [doi](https://doi.org/10.1007/bf02644249) | Table 1, p. 2, row 11; `ORC-M4S3MHU2JB.0ab219` |  |
| Lattice c | 7.914 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 10; `ORC-OC7LM6LMQC.6b17bf` |  |
| Lattice c | 7.822 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.67, Ta 0.33; λ, ε, TaFe2: Fe 0.67, Ta 0.33_ | experimental | [3] Witusiewicz 2011; _cites Elliot 1958_ | Table 1, p. 2, row 8; `ORC-V5WO5E3ST3.ae7aec` |  |
| Lattice c | 7.878 Å | 298.15 | λ, ε, TaFe2; _λ: Fe 0.666, Ta 0.334; λ, ε, TaFe2: Fe 0.666, Ta 0.334_ | unspecified | [3] Witusiewicz 2011; _cites von Keitz A 1998_ | Table 1, p. 2, row 12; `ORC-VTLJZUX2YR.dc10d5` |  |
| Lattice c | 26.98 Å | 298.15 | μ, TaFe, Ta6Fe7; _μ: Fe 0.51, Ta 0.49; μ, TaFe, Ta6Fe7: Fe 0.51, Ta 0.49_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 13; `ORC-2QZQGKG5L7.6c544a` |  |
| Lattice c | 27.07 Å | 298.15 | μ, TaFe, Ta6Fe7; _μ: Fe 0.46, Ta 0.54; μ, TaFe, Ta6Fe7: Fe 0.46, Ta 0.54_ | experimental | [3] Witusiewicz 2011; _cites Raman 1966_ | Table 1, p. 2, row 14; `ORC-44CLVSHKPS.69ee86` |  |
| Lattice c | 27 Å | 298.15 | μ, TaFe, Ta6Fe7; _μ: Fe 0.5, Ta 0.5; μ, TaFe, Ta6Fe7: Fe 0.5, Ta 0.5_ | experimental | [3] Witusiewicz 2011; _cites Kripyakevich 1968_ | Table 1, p. 2, row 15; `ORC-OQNMASIGUT.5e8387` |  |
| Lattice c | 4.85 Å | 1073.15 | UNKNOWN; _alloy: Fe 0.35, Ta 0.65_ | experimental | [3] Witusiewicz 2011; _cites Lin 1999_ [doi](https://doi.org/10.1016/s0925-8388%2899%2900138-3) | Table 1, p. 2, row 16; `ORC-RHUJ3PJKBU.36ed3a` |  |

## Sources

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

1. A Danon, C Servant, Contribution to a thermodynamic database and phase equilibria calculations for low activation Ta-containing steels, Journal of Nuclear Materials 321, 8-18 (2003). [doi:10.1016/s0022-3115(03)00196-x](https://doi.org/10.1016/s0022-3115%2803%2900196-x)
2. V.B. Rajkumar, K.C. Hari Kumar, Gibbs energy modeling of Fe–Ta system by Calphad method assisted by experiments and ab initio calculations, Calphad 48, 157-165 (2015). [doi:10.1016/j.calphad.2014.12.006](https://doi.org/10.1016/j.calphad.2014.12.006)
3. V.T. Witusiewicz, A.A. Bondar, U. Hecht, V.M. Voblikov, O.S. Fomichov, V.M. Petyukh et al., Experimental study and thermodynamic re-assessment of the binary Fe–Ta system, Intermetallics 19, 1059-1075 (2011). [doi:10.1016/j.intermet.2011.03.018](https://doi.org/10.1016/j.intermet.2011.03.018)

## 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/).