Hf
metal· Hf
Hafnium (Hf) is a dense, refractory transition metal with a hexagonal close-packed crystal structure, characterized by high melting point and excellent corrosion resistance. It is used primarily in nuclear reactor control rods, where its exceptional neutron absorption cross-section makes it the preferred choice for reactivity management in both civilian and military applications. Secondary applications include superalloy components for high-temperature aerospace engines, plasma-facing materials in fusion research, and specialized chemical catalysts; engineers select hafnium over alternatives like boron or gadolinium when neutron economy and extreme temperature stability are critical and cost is less constraining.
nuclear reactor control rodsaerospace engine componentshigh-temperature superalloysfusion reactor plasma-facing materialschemical catalysis and refiningX-ray shielding and medical devices
Compliance & Regulations
?EAR?Conflict Free?RoHS?REACH?TSCA?Prop 65
| Property | Value | Unit | Conditions | Source | |
|---|---|---|---|---|---|
Bulk Modulus(K)2 entries | 15,660.1 | ksi | — | ||
| ↳ | 15,189.8 | ksi | — | ||
Elastic Compliance Tensor(Sij) | Matrix (redacted) | 1/GPa | — | ||
Elastic Anisotropy(AU) | 0.02079 | - | — | ||
Elastic Stiffness Tensor(Cij) | Matrix (redacted) | ksi | — | ||
Poisson's Ratio(ν)2 entries | 0.2795 | - | — | ||
| ↳ | 0.3200 | - | — | ||
Shear Modulus(G)2 entries | 8,096 | ksi | — | ||
| ↳ | 3,005.2 | ksi | — |
N entriesMultiple entries per property — large groups are collapsed; click a summary row to expand. Use filters above to narrow by form / heat treatment / basis.
Verified Unverified Low confidence (<80%) Link to source
| Property | Value | Unit | Conditions | Source | |
|---|---|---|---|---|---|
Density(ρ) | 0.4922 | lb/in³ | — |
Verified Unverified Low confidence (<80%) Link to source
| Property | Value | Unit | Conditions | Source | |
|---|---|---|---|---|---|
Band Gap(Eg) | 0.000 | eV | — | ||
Magnetic Moment(μB) | 0.000 | µB | — | ||
Piezoelectric Modulus(eij) | 1.927 | C/m² | — | ||
Piezoelectric Stress Tensor(eij) | Matrix (redacted) | C/m² | — | ||
Seebeck Coefficient(S) | 1.230 | µV/K | — |
Verified Unverified Low confidence (<80%) Link to source
| Property | Value | Unit | Conditions | Source | |
|---|---|---|---|---|---|
Energy Above Hull(ΔEhull) | 0.000 | eV/atom | — | ||
Formation Energy(ΔHf) | 0.1742 | eV/atom | — |
Verified Unverified Low confidence (<80%) Link to source
Regulatory Screening
Environmental
Export Control
RoHS, REACH, and Prop 65 statuses are validated against official substance lists (ECHA SVHC Candidate List, OEHHA Prop 65, RoHS Annex II). Other regulations are estimated from composition and material classification. All screening is a starting point for due diligence — always verify with your supplier before making compliance decisions.