Golden Sunbird Metals is a leading supplier of niobium and niobium alloys in China, and we offer a comprehensive selection of niobium alloy materials, including grades such as Nb521 (Nb5W2Mo1Z), Cb-752 (Nb10W2.5Zr), and C-103 (UNS R04295 / 89Nb-10Hf-Ti), as well as customized products. With high melting points, high-temperature performance, corrosion resistance, and thermal conductivity, our Tantalum alloy products are ideal for electronics, chemical processing equipment, aerospace components, medical equipment, nuclear, automotive, and optical applications. We are committed to elevating the standards and performance of your projects. If you would like to purchase Niobium alloy products in bulk or customized Niobium alloy products, please feel free to contact [email protected].

FAQs

Niobium alloys are high-performance materials made primarily from niobium (Nb) combined with elements such as hafnium, titanium, tungsten, zirconium, or molybdenum. They deliver exceptional high-temperature strength, corrosion resistance, and mechanical stability in extreme environments, making them ideal for demanding aerospace, medical, and industrial applications.

Golden Sunbird Metals supplies premium grades including C-103 (89Nb-10Hf-Ti, UNS R04295), Nb521 (Nb5W2Mo1Zr), Cb-752 (Nb10W2.5Zr), niobium-titanium, and niobium-hafnium alloys. Each is engineered for specific high-temperature and corrosion-resistant requirements.

Niobium alloys feature high melting points, superior corrosion resistance, excellent thermal stability, high strength-to-weight ratio, and ductility. They maintain mechanical integrity at extreme temperatures, resist chemical attack, and offer biocompatibility—properties that outperform many alternatives in harsh operating conditions.

Niobium alloys and titanium alloys are both known for their exceptional strength, lightweight, and corrosion resistance. However, niobium alloys tend to have higher melting points and are better at retaining their mechanical properties at extremely high temperatures. On the other hand, titanium alloys are more abundant and less costly than niobium alloys. The choice between niobium and titanium alloys often depends on the specific requirements of the application, including temperature, weight, and cost considerations.

  • Most important information:
    • Niobium has higher melting points than titanium.
    • Niobium retains properties at higher temperatures.
    • Choice depends on application requirements and cost considerations.

C-103 (UNS R04295) is a premium niobium-based refractory alloy, also known as Nb-10Hf-1Ti. It consists of niobium as the base metal alloyed primarily with hafnium and titanium. Developed for extreme environments, it is a solid-solution strengthened alloy that delivers exceptional high-temperature strength while remaining relatively easy to fabricate and weld compared to other refractory metals.

Typical composition (weight %):

  • Niobium (Nb): Balance (≈89%)
  • Hafnium (Hf): 9.0–11.0%
  • Titanium (Ti): 0.7–1.3%
  • Zirconium (Zr): ≤0.7%
  • Tantalum (Ta): ≤0.5%
  • Tungsten (W): ≤0.5%
  • Interstitials: C ≤0.015%, O ≤0.025%, N ≤0.010%, H ≤0.0015% (exact limits per ASTM specs).
  • High-temperature performance: Retains excellent mechanical strength up to 1,482°C (2,700°F) — ideal where regenerative cooling is unavailable.
  • Density: 8.85 g/cm³ (0.32 lb/in³) — one of the lowest among refractory metals, enabling significant weight savings in aerospace components.
  • Melting point: 2,350 ± 50°C (4,260 ± 90°F).
  • Ductility & fabricability: Excellent room-temperature ductility, low ductile-to-brittle transition temperature (resists high-frequency vibrations at cryogenic temperatures down to –195°C / –320°F), and superior weldability (TIG welds perform well even after thermal cycling).
  • Other benefits: High thermal conductivity, good oxidation resistance when coated, corrosion resistance, and stability across a wide temperature range (cryogenic to extreme heat).

Mechanical properties (typical annealed bar, room temperature):

  • Tensile Strength: ~386 MPa (56 ksi)
  • Yield Strength: ~276 MPa (40 ksi)
  • Elongation: ≥20%

Elevated-temperature strength remains competitive even at 1,093°C (2,000°F).

C-103 is the go-to material for demanding propulsion and high-heat aerospace components, including:

  • Rocket engine nozzles and thrust chambers (especially orbital and high-thrust systems).
  • Missile steering (vectoring) nozzles and hypersonic vehicle components.
  • Spacecraft structural parts, satellite propulsion, and re-entry vehicle hardware.
  • Jet engine afterburner liners, seals, and flaps.
  • Other high-temperature, lightweight applications in defense, nuclear, and chemical processing where strength-to-weight ratio and thermal stability are critical.

It is widely used when titanium or nickel alloys cannot handle the sustained temperatures.

  • Better fabricability and weldability than many high-strength niobium alloys (e.g., Nb521 or Cb-752).
  • Lower density than tantalum or tungsten alloys while matching high-temp performance.
  • Proven reliability in coated rocket components (up to 10× duty cycles).
  • Cost-effective weight savings for flight-critical parts.

Niobium (Nb, formerly columbium/Cb) is a lightweight refractory metal (density 8.57 g/cm³) prized for its high melting point (~2,468°C / 4,474°F), excellent ductility, low neutron absorption, superior corrosion resistance, and superconductivity at cryogenic temperatures. The primary grades are defined in ASTM B393 (strip, sheet & plate) with corresponding specs in B392 (bar/wire) and B391 (ingot):

  • Nb521: High-strength alloy (Nb-5W-2Mo-1Zr).
  • Cb-752: High-temperature alloy (Nb-10W-2.5Zr).
  • R04200-Type 1: Reactor grade unalloyed niobium.
  • R04210-Type 2: Commercial grade unalloyed niobium.
  • R04251 (NbZr1) Type 3: Reactor grade niobium alloy containing 1% zirconium.
  • R04251 (NbZr1) Type 4: Commercial grade niobium alloy containing 1% zirconium (often referenced as R04261 in some tables).
  • R04220-Type 5: RRR (Residual Resistivity Ratio) grade pure niobium (ultra-high purity for superconductivity).

These are supplied in annealed or stress-relieved condition. Nb521 and Cb-752 are advanced solid-solution/precipitation-strengthened alloys for extreme high-temperature service; the R04xxx grades are the ASTM-standard family.

Typical compositions (weight %, per ASTM B393 and manufacturer data; balance Nb):

Grade Type Zr (%) W (%) Mo (%) Ta (max %) O (max %) C (max %) N (max %) Key Notes
R04200-Type 1 Reactor unalloyed ≤0.01 – – ≤0.10 0.015 0.01 0.01 Tightest impurities for nuclear
R04210-Type 2 Commercial unalloyed ≤0.02 – – ≤0.50 0.025 0.015 0.015 Standard purity
R04251-Type 3 Reactor Nb-1Zr 0.8–1.2 – – ≤0.10 0.015 0.01 0.01 Zr for strength + nuclear purity
R04251-Type 4 Commercial Nb-1Zr 0.8–1.2 – – ≤0.50 0.025 0.015 0.015 Zr for strength + economy
R04220-Type 5 RRR pure ≤0.01 – – ≤0.10 0.004 0.003 0.003 Ultra-low interstitials (RRR ≥300)

Interstitial limits (H, Fe, Si, etc.) are strictly controlled across all grades for ductility and performance.

  • Melting point: ~2,468°C (4,474°F) for all.
  • Density: 8.57 g/cm³ (pure); 8.6–8.9 g/cm³ (alloyed).
  • Corrosion resistance: Outstanding in most acids, salts, and liquid metals (except HF and hot concentrated oxidizing acids); self-passivating oxide layer.
  • Mechanical (annealed sheet, typical ASTM minimums / representative values):
    • Unalloyed (R04200/R04210): UTS ≥207 MPa (30 ksi), YS ≥103 MPa (15 ksi), elongation ≥20–30%.
    • Nb-1Zr (R04251 Types 3/4): UTS ≥276 MPa (40 ksi), YS ≥138 MPa (20 ksi), elongation ≥15–20%.
    • RRR (R04220): UTS ≥95 MPa, YS ≥50 MPa, elongation ≥30% (optimized for formability).
    • Nb521 & Cb-752: Superior high-temp strength (retained >1,200°C); Cb-752 excels in creep resistance to ~1,371°C.
  • Other benefits: Low thermal neutron cross-section (ideal for nuclear), excellent fabricability/weldability, superconductivity (RRR grade for RF cavities), and high thermal conductivity. Alloys provide 2–3× the elevated-temperature strength of pure niobium.
  • R04200-Type 1 & R04210-Type 2 (unalloyed): Nuclear reactor components, chemical processing equipment, superconducting RF cavities (when high-purity).
  • R04251 (NbZr1) Types 3/4: Nuclear fuel cladding, reactor internals, high-temperature furnace hardware, and structural parts needing creep resistance.
  • R04220-Type 5 (RRR): Superconducting applications — particle accelerators (e.g., LHC, SRF cavities), MRI magnets, quantum computing hardware.
  • Nb521: Aerospace rocket nozzles/thrust chambers, hypersonic vehicle components, high-temperature engine parts (stronger alternative to C-103 in some designs).
  • Cb-752: Space vehicle heat shields, rocket nozzles, nuclear reactor hardware, and coated high-temperature structures (proven in re-entry vehicles).

All grades excel where lightweight, high-temperature strength, and corrosion resistance are required beyond titanium or stainless.

  • Pure unalloyed (R04200/R04210): Maximum ductility, fabricability, and corrosion resistance; reactor grade for nuclear purity, commercial for cost-sensitive uses.
  • Nb-1Zr (R04251 Types 3/4): Zr addition boosts high-temperature strength and creep resistance while retaining excellent fabricability; reactor grade for nuclear, commercial for general industry.
  • RRR (R04220): Ultra-high purity enables superconductivity and low electrical resistance — irreplaceable for accelerators and quantum tech.
  • Nb521: Balanced medium-strength alloy with excellent high-temp performance and fabricability (often preferred over C-103 for specific strength-to-weight needs).
  • Cb-752: Highest elevated-temperature strength and creep resistance among common Nb alloys; ideal for coated extreme-heat applications (e.g., re-entry vehicles).

All maintain niobium’s core advantages (low density, weldability) while tailored for nuclear, superconducting, or propulsion demands.

Nb521 (Nb-5W-2Mo-1Zr) is a medium-strength, medium-plasticity niobium alloy strengthened by solid-solution (W and Mo) and precipitation (ZrC and related carbides) mechanisms. It was developed in China as a second-generation refractory alloy based on the former Soviet 5ВМЦ composition to overcome limitations of earlier alloys like C-103.

Cb-752 (Nb-10W-2.5Zr, also known as Nb-10W-2.5Zr or Cb752) is a classic high-strength niobium-tungsten-zirconium alloy originally developed by Haynes-Stellite (Union Carbide). It is prized for its balanced high-temperature strength, creep resistance, and room-temperature ductility in demanding thermal environments. Both alloys maintain structural integrity where most metals fail, thanks to niobium’s high melting point and the alloying additions that enhance strength without sacrificing fabricability.

Nb521 (Nb-5W-2Mo-1Zr):

  • W (Tungsten): 5.14%
  • Mo (Molybdenum): 1.87%
  • Zr (Zirconium): 1.33%
  • C (Carbon): 0.0095%
  • N (Nitrogen): 0.006%
  • O (Oxygen): 0.010%
  • Other trace elements (Cu, Ti, Fe, Si, Ta): <0.6% total
  • Nb (Niobium): Balance

Cb-752 (Nb-10W-2.5Zr):

  • W (Tungsten): 9.0–11.0%
  • Zr (Zirconium): 2.0–3.0%
  • C (Carbon): ≤0.015%
  • H (Hydrogen): ≤0.0010%
  • N (Nitrogen): ≤0.010%
  • O (Oxygen): ≤0.020%
  • Nb (Niobium/Columbium): Balance (~87.5%)
  • Nb521: Melting point 2630°C, density 8.65–9.00 g/cm³.
  • Cb-752: Melting point 2425°C, density 9.03 g/cm³. Both offer low density for weight-critical applications, excellent thermal conductivity, and low thermal expansion, making them ideal for thin-walled, high-temperature structures.

Nb521 (annealed):

  • Sheet: Tensile strength 440 MPa, yield strength 328 MPa, elongation 31%
  • Bar: Tensile strength 470 MPa, yield strength 340 MPa, elongation 36%

Cb-752 (annealed):

  • Room temperature: Tensile strength 514.5 MPa, yield strength 411.6 MPa, elongation 31%

Both exhibit good ductility and formability at room temperature, enabling complex fabrication such as spinning, forging, and welding.

Nb521 shows outstanding high-temperature strength (sheet/bar data):

  • 1450°C: Tensile ~134–157 MPa, yield ~128–130 MPa
  • 1600°C: Tensile ~93–100 MPa, yield ~81–85 MPa
  • Strength at 1600°C is 3–4 times higher than C-103 alloy. Creep resistance is also superior.

Cb-752:

  • 1093°C: Tensile 271.5 MPa, yield 221.4 MPa, elongation 45.7%
  • 1371°C: Tensile 121.5 MPa, yield 113.7 MPa, elongation >70%
  • 1645°C: Tensile 53.8 MPa, yield 53.8 MPa, elongation >45%

Nb521 is generally preferred for the highest operating temperatures, while Cb-752 excels in balanced strength-ductility across a wide range.

Neither alloy is inherently oxidation-resistant above ~500°C in air, so protective coatings are essential for service.

  • Nb521 pairs with advanced molybdenum silicide (MoSi₂) coatings (including multiphase, mullite-modified, or ZrB₂/YSZ variants) that enable continuous operation up to 1550–1600°C (or short-term higher). These coatings offer self-healing and extended life (hundreds of hours at 1500°C).
  • Cb-752 uses similar silicide or disilicide coatings for service up to ~1650°C in protected environments. Coatings dramatically extend life in rocket propulsion hot zones.
  • Nb521: Rocket engine thrust chambers, combustion chambers, nozzles, and attitude/orbit-control systems (e.g., Chinese high-thrust liquid rocket engines, Sinosat-6, lunar rover engines). It is the standard second-generation material for refractory metal thrust chambers in China’s space program.
  • Cb-752: Space propulsion components (nozzles, thrust chambers), re-entry vehicle structures, jet engine hot-section parts, nuclear reactor components, and thin-walled aerospace hardware requiring creep resistance. Both are used wherever low weight, extreme heat tolerance, and fabricability are critical—far beyond the limits of nickel or titanium alloys.
  • Vs. C-103 (Nb-10Hf-1Ti): Both Nb521 and Cb-752 offer significantly higher high-temperature strength (Nb521 is 3–5× stronger at 1600°C) and creep resistance at lower cost (no expensive hafnium). C-103 is easier to form but limited to ~1300°C service. Nb521 is the modern upgrade for higher-thrust engines.
  • Nb521 vs. Cb-752: Nb521 provides superior peak-temperature strength and creep performance with a higher melting point; Cb-752 offers higher room-temperature strength and proven heritage in U.S. re-entry programs. Choose Nb521 for maximum temperature capability; choose Cb-752 for balanced properties and legacy qualification. Both have good weldability and machinability.

Niobium alloys are widely used in aerospace (jet engine components, rocket nozzles), medical implants and MRI machines, chemical processing equipment, nuclear reactors, electronics, superconducting magnets, and optical systems where high-temperature performance and corrosion resistance are critical.

Golden Sunbird Metals provides niobium alloys in bars, sheets, plates, rods, wire, tubes, billets, strips, and crucibles. Standard and custom dimensions are available to meet precise project specifications.

All products comply with leading ASTM specifications, including ASTM B654 and B655 (C-103), ASTM B884 (niobium-titanium), ASTM B392, B393, and B394. Advanced vacuum arc and electron beam melting ensure consistent high purity and quality.

As a leading China-based manufacturer and supplier, Golden Sunbird Metals combines an extensive inventory of Niobium C-103, NbZr1 and other premium alloy grades, full customization capabilities, strict ASTM compliance, and advanced purification processes to deliver reliable, high-purity niobium alloys with superior performance and fast turnaround for global customers. Contact us at [email protected] for a competitive quote!