B–Hf system

57 accepted literature values from 4 paper(s) (experimental 20, model 32, unspecified 5); 0 calculated phase diagram(s).

Data: JSON · CSV · interactive explorer · phases (9) · papers (bibliography) · Markdown

Accepted values by evidence class
Evidence class	Values
experimental	20
model	32
unspecified	5

Accepted values by property group
Property group	Values
invariant reaction	32
phase transition	3
formation	9
heat capacity / entropy / enthalpy	8
crystal structure	5

Convex hulls: Materials Project DFT hull · OQMD DFT hull · CALPHAD hull HfB-10Kau · CALPHAD hull HfB-11Cac · CALPHAD hull HfB-97Bit-LB

Invariant reactions (literature)

Invariant reactions reported in the literature for the B–Hf system (32)
T (K)	Reaction / phases	Compositions (mole fraction)	Class	Source	Location
3653	congruent melting: L <-> HfB2	L: B 0.66; HfB2: B 0.66	experimental	[1] Bittermann 1997 cites ref. 65Rud1	Table 1, p. 2, row 1 report
3650	congruent melting: B2Hf -> Liquid	B2Hf: B 0.666667, Hf 0.333333; Liquid: B 0.666667, Hf 0.333333	model	[2] (ed.) 1998	Table I, p. 138, row 5 report
3650	congruent melting: L <-> HfB2	L: B 0.667; HfB2: B 0.667	model	[1] Bittermann 1997	Table 1, p. 2, row 3 report
3643	congruent melting: L <-> HfB2	L: B 0.667; HfB2: B 0.667	experimental	[1] Bittermann 1997 cites ref. 71Por	Table 1, p. 2, row 2 report
2506	congruent melting: L <-> βHf	L: B 0; βHf: B 0	model	[1] Bittermann 1997	Table 1, p. 2, row 6 report
2491	congruent melting: L <-> βHf	L: B 0; βHf: B 0	experimental	[1] Bittermann 1997 cites ref. 65Rud1	Table 1, p. 2, row 4 report
2473	congruent melting: L <-> βHf	L: B 0; βHf: B 0	experimental	[1] Bittermann 1997 cites ref. 71Por	Table 1, p. 2, row 5 report
2377.15	peritectic: L + HfB2 -> HfB	L: B 0.219; HfB2: B 0.667; HfB: B 0.5	model	[3] Cacciamani 2011	Table 1, p. 4, row 2 report
2377.15	peritectic: L+HfB2=HfB	L: B 0.22; HfB2: B 0.666667; HfB: B 0.5	model	[4] Pan 2021 cites Bittermann 1997 doi	Table 2, p. 5, row 3 report
2377.1	peritectic: Liquid + B2Hf -> + BHf	B2Hf: B 0.666667, Hf 0.333333; BHf: B 0.5, Hf 0.5	model	[2] (ed.) 1998	Table I, p. 138, row 2 report
2377	peritectic: L + HfB2 <-> HfB	L: B 0.22; HfB2: B 0.667; HfB: B 0.5	model	[1] Bittermann 1997	Table 1, p. 2, row 8 report
2373.15	peritectic: L+HfB2=HfB	L: B 0.2213; HfB2: B 0.666667; HfB: B 0.5	model	[4] Pan 2021	Table 2, p. 5, row 4 report
2373	peritectic: L + HfB2 <-> HfB	L: B 0.24; HfB2: B 0.66; HfB: B 0.5	experimental	[1] Bittermann 1997 cites ref. 65Rud1	Table 1, p. 2, row 7 report
2343	eutectic: L <-> HfB2 + B	L: B 0.98; HfB2: B 0.667; B: B 1	experimental	[1] Bittermann 1997 cites ref. 71Por	Table 1, p. 2, row 13 report
2338.15	eutectic: L=HfB2+(βB)	L: B 0.99; HfB2: B 0.666667; (βB): B 1	model	[4] Pan 2021 cites Bittermann 1997 doi	Table 2, p. 5, row 5 report
2338.15	eutectic: L -> HfB2 + B	L: B 0.99; HfB2: B 0.677; B: B 1	model	[3] Cacciamani 2011	Table 1, p. 4, row 3 report
2338	eutectic: L <-> HfB2 + B	L: B 0.99; HfB2: B 0.66; B: B 1	experimental	[1] Bittermann 1997 cites ref. 65Rud1	Table 1, p. 2, row 12 report
2338	eutectic: L <-> HfB2 + B	L: B 0.99; HfB2: B 0.667; B: B 1	model	[1] Bittermann 1997	Table 1, p. 2, row 14 report
2337.9	eutectic: Liquid -> β-rhombo-B + B2Hf	B2Hf: B 0.666667, Hf 0.333333	model	[2] (ed.) 1998	Table I, p. 138, row 1 report
2337.15	eutectic: L=HfB2+(βB)	L: B 0.9895; HfB2: B 0.666667; (βB): B 1	model	[4] Pan 2021	Table 2, p. 5, row 6 report
2154.15	eutectic: L -> HfB + bcc-Hf	L: B 0.15; HfB: B 0.5; bcc-Hf: B 0.01	model	[3] Cacciamani 2011	Table 1, p. 4, row 4 report
2154.15	eutectic: L=(βHf)+HfB	L: B 0.15; HfB: B 0.5	model	[4] Pan 2021 cites Bittermann 1997 doi	Table 2, p. 5, row 7 report
2154	eutectic: L <-> βHf + HfB	L: B 0.15; βHf: B 0.01; HfB: B 0.5	model	[1] Bittermann 1997	Table 1, p. 2, row 16 report
2153.6	eutectic: Liquid -> BHf + bcc-A2	BHf: B 0.5, Hf 0.5	model	[2] (ed.) 1998	Table I, p. 138, row 3 report
2153	eutectic: L <-> βHf + HfB	L: B 0.13; HfB: B 0.5	experimental	[1] Bittermann 1997 cites ref. 65Rud1	Table 1, p. 2, row 15 report
2148.15	eutectic: L=(βHf)+HfB	L: B 0.1515; HfB: B 0.5	model	[4] Pan 2021	Table 2, p. 5, row 8 report
2073	peritectoid: βHf + HfB <-> αHf	HfB: B 0.5	experimental	[1] Bittermann 1997 cites ref. 65Rud1	Table 1, p. 2, row 17 report
2066.15	peritectoid: (βHf)+HfB=(αHf)	HfB: B 0.5	model	[4] Pan 2021	Table 2, p. 5, row 10 report
2064.15	peritectoid: (βHf)+HfB=(αHf)	HfB: B 0.5	model	[4] Pan 2021 cites Bittermann 1997 doi	Table 2, p. 5, row 9 report
2064	peritectoid: βHf + HfB <-> αHf	βHf: B 0.007; HfB: B 0.5; αHf: B 0.015	model	[1] Bittermann 1997	Table 1, p. 2, row 18 report
2063.8	peritectic: bcc-A2 + BHf -> hcp-A3	BHf: B 0.5, Hf 0.5	model	[2] (ed.) 1998	Table I, p. 138, row 4 report
2063.15	peritectoid: HfB + bcc-Hf -> hcp-Hf	HfB: B 0.5; bcc-Hf: B 0.007; hcp-Hf: B 0.015	model	[3] Cacciamani 2011	Table 1, p. 4, row 5 report

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.

Enthalpies of formation, B–Hf system (9)
Phase	Compound	Value	T (K)	Class	MP DFT (kJ/mol-atom)	OQMD DFT (kJ/mol-atom)	Source	Location
HfB	HfB	-98.95 kJ/mol-atom ± 6.3	298.15	experimental	-39.896 (mp-aaaaaanh)	-40.239 (oqmd-13677)	[1] Bittermann 1997 cites ref. 64	Table 3, p. 4, row 21 report
HfB	HfB	-79.905 kJ/mol-atom		model	-39.896 (mp-aaaaaanh)	-40.239 (oqmd-13677)	[1] Bittermann 1997	Table 3, p. 4, row 22 report
HfB2	HfB2	-117.633 kJ/mol-atom	298.15	experimental	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997 cites Krupka 1962	Table 3, p. 4, row 13 report
HfB2	HfB2	-109.633 kJ/mol-atom ± 2.93333	298.15	experimental	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997 cites ref. 67Joh	Table 3, p. 4, row 15 report
HfB2	HfB2	-106.567 kJ/mol-atom	298.15	experimental	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997 cites ref. 64	Table 3, p. 4, row 14 report
HfB2	HfB2	-106.567 kJ/mol-atom		model	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997	Table 3, p. 4, row 20 report
HfB2	HfB2	-105.033 kJ/mol-atom	298.15	experimental	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997 cites Paderno 1959	Table 3, p. 4, row 12 report
HfB2	HfB2	-87.3 kJ/mol-atom ± 1.66667	298.15	experimental	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997 cites Maslov 1978	Table 3, p. 4, row 17 report
HfB2	HfB2	-83.1333 kJ/mol-atom ± 1.96667	298.15	experimental	-98.211 (mp-aaaaacys)	-98.749 (oqmd-5848)	[1] Bittermann 1997 cites Kitpichev 1979	Table 3, p. 4, row 18 report

Other properties

Phase transition (3)

Phase transition, B–Hf system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Phase transition	3650.15 K	3650.15	congruent melting: L=HfB2 L: B 0.667; HfB2: B 0.666667	model	[4] Pan 2021 cites Bittermann 1997 doi	Table 2, p. 5, row 1 report
Phase transition	3651.15 K	3651.15	congruent melting: L -> HfB2 L: B 0.667; HfB2: B 0.667	model	[3] Cacciamani 2011	Table 1, p. 4, row 1 report
Phase transition	3651.15 K	3651.15	congruent melting: L=HfB2 L: B 0.6666; HfB2: B 0.666667	model	[4] Pan 2021	Table 2, p. 5, row 2 report

Heat capacity / entropy / enthalpy (8)

Heat capacity / entropy / enthalpy, B–Hf system
Property	Value	Phases / composition	Class	Source	Location
Entropy printed: S0	22.235 J/mol-atom/K	HfB alloy: Hf 0.5	model	[1] Bittermann 1997	Table 3, p. 4, row 22 report
Entropy printed: S0	14.3667 J/mol-atom/K ± 0.133333	HfB2 alloy: Hf 0.333333	experimental	[1] Bittermann 1997 cites ref. 89Bol	Table 3, p. 4, row 19 report
Entropy printed: S0	14.2967 J/mol-atom/K	HfB2 alloy: Hf 0.333333	model	[1] Bittermann 1997	Table 3, p. 4, row 20 report
Entropy printed: S0	14.2967 J/mol-atom/K	HfB2 alloy: Hf 0.333333	experimental	[1] Bittermann 1997 cites Westrum 1977 doi	Table 3, p. 4, row 16 report
Heat capacity printed: Cp0	18.385 J/mol-atom/K	HfB alloy: Hf 0.5	model	[1] Bittermann 1997	Table 3, p. 4, row 22 report
Heat capacity printed: Cp0	16.49 J/mol-atom/K	HfB2 alloy: Hf 0.333333	experimental	[1] Bittermann 1997 cites ref. 89Bol	Table 3, p. 4, row 19 report
Heat capacity printed: Cp0	16.6033 J/mol-atom/K	HfB2 alloy: Hf 0.333333	model	[1] Bittermann 1997	Table 3, p. 4, row 20 report
Heat capacity printed: Cp0	16.5967 J/mol-atom/K	HfB2 alloy: Hf 0.333333	experimental	[1] Bittermann 1997 cites Westrum 1977 doi	Table 3, p. 4, row 16 report

Crystal structure (5)

Crystal structure, B–Hf system
Property	Value	T (K)	Phases / composition	Class	Source	Location
Lattice a	0.65185 not_printed	298.15	HfB alloy: Hf 0.5	unspecified	[1] Bittermann 1997 cites ref. 65Rud1	Table 2, p. 3, row 6 report
Lattice a	0.31438 not_printed ± 2.000e-5	298.15	HfB2 alloy: Hf 0.333333	unspecified	[1] Bittermann 1997 cites ref. 85Vil	Table 2, p. 3, row 7 report
Lattice b	0.3216 not_printed	298.15	HfB alloy: Hf 0.5	unspecified	[1] Bittermann 1997 cites ref. 65Rud1	Table 2, p. 3, row 6 report
Lattice c	0.492 not_printed	298.15	HfB alloy: Hf 0.5	unspecified	[1] Bittermann 1997 cites ref. 65Rud1	Table 2, p. 3, row 6 report
Lattice c	0.34793 not_printed ± 2.000e-5	298.15	HfB2 alloy: Hf 0.333333	unspecified	[1] Bittermann 1997 cites ref. 85Vil	Table 2, p. 3, row 7 report

Sources

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

H. Bittermann, P. Rogl, Critical assessment and thermodynamic calculation of the ternary system boron-hafnium-titanium (B-Hf-Ti), JPE 18, 24-47 (1997). doi:10.1007/bf02646757
I. Ansara, A. T. Dinsdale, M. H. Rand (eds.), COST 507: Thermochemical database for light metal alloys, Volume 2, EUR 18499 EN, Office for Official Publications of the European Communities, Luxembourg (1998), ISBN 92-828-3902-8.
G. Cacciamani, P. Riani, F. Valenza, Equilibrium between MB2 (M=Ti,Zr,Hf) UHTC and Ni: A thermodynamic database for the B–Hf–Ni–Ti–Zr system, Calphad 35, 601-619 (2011). doi:10.1016/j.calphad.2011.10.003
Yafei Pan, Lei Huang, Jiuxing Zhang, Yong Du, Fenghua Luo, Shuyan Zhang, Thermodynamic Assessment of the Ternary B-Hf-Zr System with Refined B-Hf Description, J. Phase Equilib. Diffus. 42, 864-878 (2021). doi:10.1007/s11669-021-00928-3

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). doi:10.5281/zenodo.23735569
R. Arróyave, J. Saal, D. Shin, ORCHID-Hulls: binary convex hulls (Materials Project, OQMD, assessed CALPHAD) (version 2026.10), Zenodo (2026). doi: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). doi:10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0); B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file. Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

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

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

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}