Cast supealoyCobalt based alloyPrecision alloySUPER ALLOY
Refractory metal
Titanium & Zirconium alloy
Sputtering taget
Hafnium (Hf)
1. Product Overview
Hafnium (Hf, atomic number 72) is a silvery-gray, high-density rare refractory metal with a melting point of 2233 °C and a density of 13.31 g/cm³. It offers three capabilities that are difficult to replace with any other material: an extremely high thermal neutron absorption cross section (approximately 104 barns, making it the preferred material for control rods), corrosion resistance comparable to that of zirconium, and its oxide HfO₂, which has a dielectric constant as high as 18–25 and serves as the base material for high-k gate dielectrics in advanced semiconductor nodes.
The three key decision points in material selection are: whether the zirconium (Zr) content is controlled (hafnium and zirconium occur together in nature, and this is the core of the price difference), the certification grade (nuclear grade R1 or commercial grade R3), and the product form and dimensional tolerances. Nuclear and semiconductor grades require zirconium contents down to a few hundred ppm, which makes refining costly and can drive the price to several times that of the industrial grade.
Hafnium (element symbol Hf, atomic number 72) is chemically very similar to zirconium and almost always occurs together with zirconium in minerals such as zircon. This "twin" relationship has two direct consequences: first, hafnium can only be obtained by separation from zirconium, and the separation process is complex and costly; second, for the nuclear industry, zirconium must be freed of hafnium (zirconium is required to be "neutron transparent"), while hafnium, precisely because it strongly absorbs neutrons, becomes the control rod material — each is the impurity of the other.
Melting Point | Density | Thermal Neutron Absorption Cross Section | Standard Purity Grade |
2233 °C | 13.31 g/cm³ | ≈104 barns | 4N–4N5 |
Beijing Zhongye Xincai Technology Co., Ltd. manufactures and supplies hafnium and hafnium products covering metal ingots, granules, rods, wires, plates, strip and foil, powders, sputtering targets, and fabricated parts customized to drawings. Production and acceptance can be organized in accordance with ASTM B737, ASTM B776, or a technical agreement between both parties, and chemical composition analysis reports and material certificates are supplied with the goods.
Overview of Main Product Forms — Beijing Zhongye Xincai Technology Co., Ltd.
Hafnium ingot / granules: vacuum melted, purity 4N–4N5, used for alloying additions, remelting and research.
Hafnium rod / wire: to ASTM B737, available forged, hot-rolled, cold-rolled, ground and annealed; hafnium wire for plasma cutting electrodes is a standard stock item.
Hafnium plate / strip / foil: to ASTM B776, hot-rolled, cold-rolled and annealed, with a ground or alkaline-pickled surface finish.
High-purity hafnium powder and hafnium oxide powder (HfO₂): used for ceramics, thermal spraying, target fabrication and catalysis.
Sputtering targets: metallic hafnium targets and hafnium dioxide targets, round or rectangular, available with backing plate bonding.
Custom fabricated parts: crucibles, heat shields, nozzle electrodes, flanges and special-shaped parts, machined to drawings.
2. Key Performance Parameters
Typical Physical Properties of Hafnium (Room Temperature, Reference Values)
Item | Typical Value | Item | Typical Value |
Element symbol / atomic number | Hf / 72 | Density (20 °C) | 13.31 g/cm³ |
Atomic weight | 178.49 | Melting point | 2233 °C |
CAS No. | 7440-58-6 | Boiling point | 4603 °C |
Crystal structure | Hexagonal close-packed (α phase); transforms to body-centered cubic at high temperature | Thermal conductivity | ≈23 W/(m·K) |
Electrical resistivity (20 °C) | ≈33 µΩ·cm | Coefficient of thermal expansion | ≈5.9×10⁻⁶ /K |
Specific heat capacity | ≈0.144 J/(g·K) | Elastic modulus | ≈78 GPa |
Poisson's ratio | ≈0.37 | Thermal neutron absorption cross section | ≈104 barns |
Appearance | Silvery-gray metallic luster | Recrystallization temperature | ≈700–850 °C |
Note: The values in the table above are typical data compiled from publicly available sources and vary with purity, processing condition and test temperature. Formal acceptance shall be based on the material certificate (MTC) supplied with the goods and the technical agreement between both parties. |
Form and Sampling Direction | Test Temperature | Tensile Strength (min.) | Yield Strength (min.) | Elongation (min.) |
Rod · longitudinal | Room temperature | 400 MPa | 151 MPa | 22% |
Plate · longitudinal | Room temperature | 400 MPa | 151 MPa | 20% |
Plate · transverse | Room temperature | 310 MPa | 172 MPa | 20% |
Plate · longitudinal | 315 °C | 172 MPa | 76 MPa | 25% |
Plate · transverse | 315 °C | 158 MPa | 96 MPa | 30% |
Annealed hafnium has excellent ductility and formability and can be cold rolled, stamped, bent and deep drawn; after work hardening, ductility must be restored by vacuum annealing. Hafnium has a low yield-to-tensile ratio and a mild tendency to work harden, making it one of the more formable refractory metals.
Chemical composition limits for hafnium to ASTM B776 / B737 (wt%, balance Hf)
Element | R1 (Nuclear Grade) | R3 (Commercial Grade) | Element | R1 (Nuclear Grade) | R3 (Commercial Grade) |
Al | 0.01 | 0.05 | N | 0.01 | 0.02 |
C | 0.02 | 0.03 | O | 0.04 | 0.13 |
Cr | 0.01 | 0.05 | Si | 0.01 | 0.05 |
Cu | 0.01 | — | Ta | 0.02 | — |
Fe | 0.05 | 0.08 | Ti | 0.01 | 0.05 |
H | 0.0025 | 0.01 | W | 0.02 | 0.02 |
Mo / Ni / Nb | 0.01 | — | V | 0.01 | — |
Sn | 0.01 | — | Zr | Reported value | Reported value |
R1 is the nuclear grade, with extremely strict control of neutron-absorbing impurity elements (such as B and Cd) and gaseous elements; it is used in critical parts such as nuclear reactor control rods. R3 is the commercial grade, with relatively relaxed impurity limits, and is used mainly for alloying additions, the chemical industry and general industrial applications.
Table 5-1 Common Product Forms and Specification Ranges (actual available specifications are subject to confirmation at the time of order)
Form | Common Specification Range | Delivery Condition | Reference Standard |
Hafnium ingot / granules | 1–25 kg per ingot; granules by mesh size | Vacuum melted / crushed and screened | Technical agreement |
Hafnium rod | φ3–60 mm, length ≤ 2000 mm | Forged, hot-rolled, ground, annealed | ASTM B737 |
Hafnium wire | φ0.5–6.0 mm (φ1.5 / 1.6 / 2.4 / 3.0 / 3.2 mm commonly used for plasma cutting) | Cold drawn, annealed, cut to length | ASTM B737 |
Hafnium plate | Thickness 0.5–20 mm, width ≤ 600 mm | Hot-rolled, cold-rolled, annealed | ASTM B776 |
Hafnium strip / foil | Thickness 0.05–0.5 mm, width 10–300 mm | Cold-rolled, annealed | ASTM B776 |
Hafnium powder / hafnium oxide powder | Particle size by mesh or D50 as agreed; purity 3N–4N5 | Atomization / hydride-dehydride / chemical process | Technical agreement |
Sputtering target | Round target φ50–300 mm; rectangular target per drawing; copper backing plate bonding available | Machined, polished, clean-packed | Technical agreement |
Custom fabricated parts | Crucibles, heat shields, nozzles, flanges, special-shaped parts | Machining / welding / surface treatment | Per drawing |
The hafnium and hafnium products manufactured and supplied by Beijing Zhongye Xincai Technology Co., Ltd. are high-value, small-batch materials, and the great majority of orders are made to order; stock items are mainly hafnium wire, hafnium rod and small-size plate in standard specifications. For custom specifications, drawings or explicit requirements for dimensions, tolerances, condition and testing must be provided at the enquiry stage.
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