1J79 Supermalloy (80Ni-Fe Soft Magnetic Alloy) – Supplier of High Permeability Strip, Bar & Wire | Shanghai Hangbo Alloy Group

By Shanghai Hangbo Alloy Group Co., Ltd. | ISO 9001:2015 Certified | Est. 2012 | Shanghai, China

Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp: +86 13611656360

Quick Answer: What Is 1J79 Permalloy?

1J79 (Supermalloy / 80Ni-Fe / Mo-Permalloy) is a premium nickel-iron soft magnetic alloy with approximately 80% nickel and 5% molybdenum that delivers extreme maximum permeability (typically ≥300,000 μₘ) and ultra-low coercivity (≤1.6 A/m) after specialized hydrogen annealing. It is the metallurgical benchmark for high-sensitivity magnetic components including magnetic shields for electron microscopes, high-precision current transformer cores, and fluxgate magnetometer sensors. Shanghai Hangbo Alloy Group supplies 1J79 in precision cold-rolled strip, round bar, and wire with certified magnetic properties per GB/T 14985.

Industry Pain Point: Electronic sensor manufacturers often struggle with signal noise and phase-shift errors when using standard magnetic alloys in low-field applications. 1J79 Supermalloy — with initial permeability 5–10× higher than 1J50 and coercivity 10× lower — eliminates the magnetic hysteresis "floor" that masks weak signals, enabling measurement sensitivities into the nano-Tesla range that are physically impossible with lower-nickel grades.

Key Properties at a Glance

Product Overview

1J79 represents the apex of the nickel-iron magnetic alloy system. While 50% nickel alloys (1J50) are chosen for power handling and high flux density, 1J79 is the "small signal" specialist. By increasing the nickel content to the 79–80% range and adding 4–5% molybdenum, the alloy achieves near-zero magnetocrystalline anisotropy and near-zero magnetostriction simultaneously — the fundamental requirement for extreme magnetic permeability.

The 1J79 value proposition centers on Sensitivity and Shielding Efficiency:

• Ultra-High Sensitivity: Initial permeability (μᵢ) typically exceeds 40,000, allowing the alloy to respond to extremely weak magnetic fields (such as the Earth's magnetic field or biological magnetic signals) that would fail to "wake up" the magnetic domains in silicon steel or 50% Ni Permalloys.
• Superior Shielding Factor: In magnetic shielding applications, 1J79 provides the highest attenuation per unit thickness for low-frequency (DC to 10 kHz) fields. A single layer of 1J79 can reduce ambient magnetic noise by 100–1000×, essential for SQUID sensors and high-resolution imaging.
• Low Core Loss: The combination of high resistivity (~0.55 μΩ·m) and ultra-low coercivity results in minimal hysteresis and eddy current losses, making it ideal for high-frequency pulse transformers and sensitive relay armatures.

The "Supermalloy" Distinction: Standard 1J79 meets high permeability requirements, but "Supermalloy" refers to a subclass of 1J79 produced via ultra-clean vacuum induction melting (VIM) and complex multi-stage annealing that pushes max permeability toward the 500,000+ range. Shanghai Hangbo Alloy Group supplies both standard 1J79 and premium Supermalloy-grade material.

Executive Standards

Chemical Composition (wt.% per GB/T 14985 – 100% OES + ICP-MS Verified)

Trace Element Control: For 1J79, "Commercially Pure" is not enough. Sulfur and Carbon must be managed at the ppm level because the alloy's performance depends on long-range magnetic ordering that is disrupted by even microscopic non-metallic inclusions. VIM melting is the only reliable route to achieving 1J79 specifications.

Magnetic Properties (per GB/T 14985, after H₂ Annealing)

Physical & Mechanical Properties

Heat Treatment: The "Final Anneal" Secret

1J79 is the most process-sensitive alloy in the precision catalog. Its properties in the as-rolled condition are negligible; the high permeability is "born" in the final hydrogen anneal.

Specialized 1J79 H₂ Annealing Schedule

Why −60°C Dew Point? Standard "dry" hydrogen (−40°C) is insufficient for 1J79. At 1150°C, the trace moisture in −40°C H₂ is enough to selectively oxidize the ~5% molybdenum at the surface, creating an "oxide skin" that exerts mechanical stress on the magnetic domains, capping max permeability at ~100,000. To reach 300,000+, the atmosphere must be essentially bone-dry (−60°C) to allow molybdenum to remain in metallic solid solution at the surface.

Shock Sensitivity: Once annealed, 1J79 is extremely sensitive to mechanical stress. Dropping an annealed shield or over-tightening a mounting screw introduces dislocations that instantly drop permeability by 30–70%. Components should be annealed in their final shape and handled with "surgical" care.

Production Process

1. Cold-Rolled Strip & Sheet

• VIM Melting: 100% VIM required for carbon and sulfur control. Molybdenum (Mo) is added as pure metal, not ferro-moly, to prevent impurity carry-over.
• Cold Rolling: Multi-pass reduction with intermediate hydrogen anneals. For ultra-thin "ribbon" (0.02–0.05 mm), precision Sendzimir mills are used to maintain ±0.002 mm thickness tolerance — critical for uniform flux distribution in wound cores.
• Final Supply Condition: Usually supplied "as-rolled" (work-hardened) to allow the customer to stamp/form parts. Magnetic properties are certified on sample coupons annealed alongside the production lot.

2. Hot-Rolled Bar & Plate

• Forging/Rolling: ESR ingots hot-worked at 1100–1180°C. Minimum 4:1 reduction.
• Conditioning: Peeled or ground to remove the surface layer. For large magnetic shields (MRI, etc.), plate flatness is controlled to ≤ 2 mm/m.
• Certification: Each bar heat is certified for DC magnetic properties (μᵢ, μₘ, Hc) on an annealed test ring.

Industry Applications

Quality Assurance: 7-Stage Zero-Defect Inspection

1. Charge Material Purity: Every kg of Ni and Mo is ICP-MS verified for boron, sulfur, and carbon. Total impurity budget < 200 ppm.
2. VIM Melt Surveillance: Carbon verified ≤ 0.015% at tap. Oxygen monitored to ≤ 10 ppm.
3. Internal Stress Mapping: Cold-rolled strip samples checked for uniform work-hardening distribution — non-uniform stress leads to "warping" during the final H₂ anneal.
4. H₂ Atmosphere Monitoring: In-line laser hygrometer records dew point continuously. Any excursion above −50°C triggers lot quarantine.
5. Magnetic Ring Testing: Per GB/T 3658. Initial and maximum permeability measured on 100% of heat-treatment lots.
6. Dimensional Verification: Strip thickness verified to ±0.005 mm or better.
7. Vacuum Packaging: 1J79 contains ~15% Fe and is susceptible to rust. All exports are vacuum-sealed with VCI (Volatile Corrosion Inhibitor) paper and desiccant.

Frequently Asked Questions

Q1: What is 1J79 used for?

1J79 is the premier choice for ultra-high sensitivity magnetic shielding and high-precision sensors. It is used for shielding electron microscopes, SQUID magnetometers, and medical EEG/MEG rooms. In sensors, it forms the core of high-accuracy (class 0.1) current transformers and fluxgate magnetometers. It is selected whenever the magnetic field to be detected or shielded is extremely weak (below 0.1 mT).

Q2: What is the density of 1J79?

8.65 g/cm³ (0.313 lb/in³) — higher than 50% Ni grades (8.20 g/cm³) because nickel is denser than iron.

Q3: What is the saturation flux density (Bs) of 1J79?

Approximately 0.75 T (7,500 G). This is much lower than 1J50 (~1.55 T). 1J79 is NOT a power alloy; it will saturate if exposed to strong fields or high currents. Its strength lies in sensitivity, not capacity.

Q4: What is the maximum service temperature?

The Curie temperature is ~450°C. For stable magnetic performance, the operating temperature should be kept below 200°C. As the temperature approaches the Curie point, permeability drops sharply.

Q5: How does 1J79 compare to 1J50?

1J79 has 3–5× higher permeability and 10× lower coercivity, making it far more sensitive. However, 1J50 has 2× higher saturation, making it better for handling high magnetic flux. Use 1J79 for sensitivity/shielding; use 1J50 for power/transformers.

Q6: Can I machine 1J79 after annealing?

NO. Any machining (drilling, grinding, even heavy clamping) after the final H₂ anneal introduces mechanical stress that destroys the high-permeability properties. All shaping must be done BEFORE the final magnetic anneal.

Q7: What is the difference between 1J79 and Mu-metal?

Technically, Mu-metal is a trade name for the 80Ni-5Mo-Fe family. 1J79 is the Chinese GB standard equivalent. They are functionally interchangeable if the molybdenum and nickel contents are matched.

Q8: Is 1J79 magnetic?

Yes, it is a soft magnetic alloy. It is strongly attracted to magnets, but it does not "stay" magnetic (low remanence) once the external field is removed.

Q9: What heat treatment does it require?

Hydrogen annealing at 1150–1200°C with an ultra-dry atmosphere (dew point ≤−60°C) and a controlled slow cool through the Curie range.

Q10: Why is 1J79 so expensive?

It contains ~80% high-purity nickel and ~5% molybdenum, both expensive commodities. Additionally, the VIM melting and ultra-dry hydrogen annealing are high-energy, low-yield specialized processes.

Q11: What product forms are available?

Shanghai Hangbo supplies 1J79 in cold-rolled strip (0.02–2.5 mm), round bars (Ø6–200 mm), wire, and plates.

Q12: Is it weldable?

Yes, but welding destroys magnetic properties in the HAZ. The entire assembly must be re-annealed after welding.

Q13: Does it rust?

Yes. Despite the 80% nickel, the remaining iron makes it susceptible to atmospheric corrosion. It should be kept in dry storage or plated (nickel/gold) for protection.

Q14: What is Supermalloy?

Supermalloy is a premium grade of 1J79 with max permeability pushed above 300,000–500,000 through ultra-pure melting and advanced thermal cycling.

Q15: Does Shanghai Hangbo ship internationally?

Yes, we export 1J79 to 40+ countries (USA, Germany, Japan, etc.) with full EN 10204 3.1 certification.

Q16: How do I order?

Email sales@hangboalloy.com with your dimensions (thickness/width/length) and the required permeability level.

Contact Shanghai Hangbo Alloy Group