Description
Ultimate 1J79 Permalloy Sheet – High‑Performance Magnetic Shielding Alloy
📌 Executive Summary
The 1J79 Permalloy Sheet is a precision soft magnetic nickel‑iron alloy engineered for ultra‑high permeability and exceptionally low coercivity. Leveraging a nominal chemistry of Ni 78.5–80.0%, Mo 4.0–5.0%, Fe balance, the alloy provides outstanding magnetic response in weak‑field environments, minimal hysteresis loss, and stable performance after magnetic annealing. This document presents a comprehensive, data‑rich overview of 1J79 Permalloy Sheet for engineering selection, design, processing, and quality verification.
Learn how wrought Ni‑Fe soft magnetic alloys are defined and verified in ASTM standards for soft magnetic alloys.
🎯 Why Choose 1J79 Permalloy Sheet
- Ultra‑high permeability (μmax typically ≥ 80,000; application‑tuned even higher)
- Very low coercivity (Hc typically ≤ 2 A/m in annealed state)
- Excellent magnetic shielding for low‑frequency fields and precision instrumentation
- Low core loss in sensitive DC/low‑frequency magnetic circuits
- Good processability (shearing, punching, laser cutting, forming) with proper practice
- Stable, repeatable properties after controlled‑atmosphere magnetic annealing
- Robust supply in sheets, plates, strips, and foils, with tight dimensional control
This combination positions 1J79 Permalloy Sheet as a go‑to material for EMI mitigation at low frequency, transformer cores, precision sensors, magnetic head components, and scientific instrumentation.
🧪 Chemical Composition (Typical, wt%)
| Element | Ni | Mo | Fe |
|---|---|---|---|
| Content (%) | 78.5 – 80.0 | 4.0 – 5.0 | Balance |
Notes
- Copper, silicon, carbon, sulfur, oxygen, and other residuals are limited to tight maxima to preserve magnetic cleanliness.
- Melt routes typically include vacuum induction melting (VIM) and vacuum arc remelting (VAR) or equivalent to assure homogeneity for the 1J79 Permalloy Sheet.
📐 Dimensional Supply & Tolerances
We supply 1J79 Permalloy Sheet and 1J79 Permalloy Plate across a broad thickness spectrum with tight flatness and thickness control.
| Product Form | Thickness Range | Standard Sheet Size | Typical Flatness | Thickness Tolerance | Edge Condition |
|---|---|---|---|---|---|
| Sheet / Plate | 0.20 – 5.00 mm | 800 × 800 mm (other sizes on request) | ≤ 0.5 mm per 1000 mm | ±(0.03–0.08) mm (by gauge) | Sheared, deburred |
| Strip (coil) | 0.05 – 1.00 mm | Widths up to 300 mm | ≤ 2.0 mm/m | ±(0.01–0.03) mm | Slit, burr‑controlled |
| Foil | 0.02 – 0.10 mm | Custom sheets & coils | ≤ 2.0 mm/m | ±(0.005–0.01) mm | Film‑protected |
Surface finish (annealed, bright): Ra ≤ 0.8–1.6 μm typical; finer finishes on request.
Flatness options: stress‑relief‑annealed sheets for critical lamination packs.
Coatings: insulating/varnish coatings available for lamination designs.
📊 Physical & Magnetic Properties (Typical)
| Property | Symbol | Typical Value | Comments |
|---|---|---|---|
| Density | ρ | 8.7 g/cm³ | Mass estimation, inertia calculations |
| Electrical Resistivity | ρe | ≈ 0.45–0.60 μΩ·m | Higher than low‑Ni steels → lower eddy‑current loss |
| Curie Temperature | Tc | ~ 450 °C | Above which ferromagnetism vanishes |
| Saturation Induction | Bs | ≥ 0.8 T | Lower than Si‑steel but adequate for shielding & sensors |
| Max Permeability | μmax | ≥ 80,000 | Post magnetic anneal; geometry dependent |
| Initial Permeability | μi | ≥ 15,000 | Post magnetic anneal |
| Coercive Force | Hc | ≤ 2.0 A/m | Post magnetic anneal, weak‑field optimized |
| Hardness (annealed) | HV | ~ 130–160 | Work‑hardens with forming/cold work |
Engineering note: Actual values depend on thickness, geometry, cold‑work level, annealing recipe, and test method (ring cores, Epstein frames, DC/AC conditions). For critical designs, specify acceptance criteria and test geometries alongside the procurement of 1J79 Permalloy Sheet.
🧭 Magnetic Performance vs. Frequency (Illustrative)
| Frequency | μi (typ.) | μmax (typ.) | Core Loss Trend | Use Case |
|---|---|---|---|---|
| DC – 50 Hz | 15,000+ | 80,000+ | Lowest | Magnetic shielding, precision DC transformers |
| 50 – 400 Hz | 12,000–15,000 | 60,000–80,000 | Low | Audio/measurement transformers, chokes |
| 400 Hz – 1 kHz | 8,000–12,000 | 40,000–60,000 | Moderate | Specialized sensors, low‑power cores |
| > 1 kHz | ↓ | ↓ | ↑ | Consider thinner gauges or alternate materials |
For high‑frequency EMI above several kHz, shielding behavior is governed more by conductivity and skin depth rather than purely by permeability; for low‑frequency magnetic shielding, 1J79 Permalloy Sheet remains superior due to high μ.
🔩 Mechanical Properties (Indicative)
| Condition | YS (0.2% offset) | UTS | Elongation | Modulus E |
|---|---|---|---|---|
| Annealed | 200–300 MPa | 400–550 MPa | 25–40% | ~ 190–210 GPa |
| 20–40% Cold‑Worked | 350–500 MPa | 600–800 MPa | 5–20% | — |
Caution: Cold work degrades magnetic softness; plan a final magnetic anneal after forming the 1J79 Permalloy Sheet parts to restore permeability and reduce Hc.
🔥 Heat Treatment & Magnetic Annealing
- Stress‑Relief Anneal (SRA): 700–900 °C for 1–2 h, protective atmosphere; cool at ≤ 50 °C/h to limit residual stresses.
- Magnetic Anneal (MA): 1050–1200 °C, hydrogen or high‑purity inert atmosphere, 2–4 h soak; very slow cool (≤ 20–50 °C/h) to < 200 °C.
- Degassing/Deoxidation: Moisture/oxygen control is critical; dew point ≤ −40 °C recommended.
- Optional Field Anneal: Some applications employ low DC bias field during cool‑down to set preferred domain orientation (consult design).
Do: machine/blank the 1J79 Permalloy Sheet to near‑net before MA; minimize handling damage and avoid contamination.
Don’t: weld after MA without re‑anneal; avoid sharp bends and excessive forming after MA.
🛠️ Fabrication Guidance
Cutting & Blanking
- Laser cutting: Use nitrogen/argon assist for clean edges; moderate heat input to prevent local property deterioration.
- Punching: Clearance ≈ 4–8% of thickness; maintain sharp tooling; deburr gently to keep edge damage minimal.
- Shearing: Back‑up support with minimal rake to reduce camber; straight‑edge finish preferred for stacking.
Forming & Bending
- Minimum inside bend radius r ≥ 1.0×t (annealed). For tighter bends, intermediate SRA recommended.
- Limit total cold work to preserve magnetic softness; plan final MA.
Machining
- Conventional carbide tooling with modest speeds; avoid work‑hardening by positive rake and adequate coolant.
- Final fine‑grind before MA if mirror finish shields are required.
Joining
- Spot welding/TIG viable before MA; keep HAZ small and clean.
- Brazing with Ni‑based fillers possible; thoroughly degrease, and re‑anneal after joining for magnetic restoration.
🧲 Magnetic Shielding Design Guide (Practical Notes)
Shielding Factor, first‑order (long cylinder approximation):
S≈1+μr⋅tDS \approx 1 + \frac{\mu_r \cdot t}{D}
where μr is relative permeability, t is wall thickness, D is diameter (or characteristic dimension). With 1J79 Permalloy Sheet at high μ, multi‑layer shields achieve large S even at modest thickness.
Design tips
- Multiple concentric layers (2–3 shells) yield multiplicative shielding gains: Stotal≈S1×S2×S3S_{total} ≈ S_1 × S_2 × S_3.
- Avoid gaps and magnetic leaks: overlap seams, use labyrinth joints, and keep fasteners of compatible alloy.
- Demagnetization: De‑gauss assemblies after handling/bending; a progressive AC de‑mag routine improves low‑field performance.
- Orientation: Align long shields with field lines when possible to reduce demagnetizing factors.
- Saturation check: For strong fields, ensure B in the shield wall remains below ~0.6–0.8 T; consider thicker wall or larger radius.
According to IEEE Magnetic Society Publications, low‑frequency shielding effectiveness grows with material permeability and continuity of the magnetic path—both of which are core strengths of 1J79 Permalloy Sheet.
🔄 Comparison with Alternative Soft Magnetic Alloys
| Property | 1J79 Permalloy Sheet | 1J85 (High‑Ni Permalloy) | 1J50 (≈50Ni‑Fe) | Grain‑Oriented Si‑Steel | “Mu‑metal” class |
|---|---|---|---|---|---|
| Ni content | ~79% | ~80% (often higher Mo/Cu tuning) | ~50% | — | ~77–80% (with Cu, Mo) |
| μmax (post MA) | 80k+ | 100k+ potential | 25k–40k | 30k–40k (GO) | 80k–100k |
| Hc (A/m) | ≤ 2 | ≤ 1.5 | 2–6 | 5–10 | ≤ 1.5 |
| Bs (T) | ~0.8 | ~0.7–0.8 | ~1.5 | ~2.0 | ~0.7–0.8 |
| Resistivity (μΩ·m) | 0.45–0.60 | 0.5–0.6 | 0.6–0.7 | 0.45–0.5 | 0.5–0.6 |
| Best use | Low‑freq shielding, precision cores | Ultra‑low Hc, lab shielding | Higher Bs, mid‑μ cores | High Bs, power transformers | Extreme low Hc, lab shields |
Takeaway: 1J79 Permalloy Sheet delivers an optimal balance of very high μ and practical Bs for most low‑frequency shielding and precision magnetics, while materials like Si‑steel suit high‑flux power applications.
🧰 Applications & Case Patterns
- Magnetic shielding: instrument enclosures, MRI room components (ancillary low‑field parts), photomultiplier tubes, SQUID and lab shields.
- Precision transformers: measurement transformers, audio transformers where low noise is critical.
- Sensors & actuators: fluxgate cores, current sensors, magnetic amplifiers, relays requiring low magnetizing force.
- Recording & guidance: magnetic heads, navigation and stabilization systems mitigating stray fields.
- Research: field concentrators, magnetic flux shunts, experimental fixtures.
Case example (illustrative): A two‑layer cylindrical shield of 1J79 Permalloy Sheet, each layer t = 1.0 mm, D = 120 mm, achieves first‑order SS in the 10³–10⁴ range for quasi‑DC ambient fields when post‑assembled de‑gaussed and magnetically annealed components are used. Actual performance must be validated on geometry‑accurate test rigs.
📦 Packaging, Handling & Storage
- Vacuum or VCI wrap to inhibit oxidation; paper interleaves protect surfaces.
- Edge guards and poly caps for strips/coils.
- Export‑grade wooden cases with humidity indicators and shock labels.
- Store 1J79 Permalloy Sheet in dry indoor conditions; avoid magnetic contamination from strong permanent magnets near storage.
🔍 Quality Assurance & Documentation
- Chemical composition by OES/ICP to certify Ni, Mo, Fe ranges.
- Magnetic tests: coercivity (Hc), permeability (μi, μmax) using standard ring/strip methods (IEC 60404 series).
- Dimensional inspection: thickness, flatness, edge burr, camber, residual stress checks.
- Surface integrity: Ra, visual defects, oxide and discoloration limits.
- Certificates: EN 10204 3.1 MTR, heat identity, process route, and anneal conditions where applicable.
- Traceability: heat/batch numbers on packaging and labels for every lot of 1J79 Permalloy Sheet and 1J79 Permalloy Plate.
🧯 Safety & Environmental
- Compliant with RoHS and REACH directives.
- Hydrogen annealing performed under controlled safety protocols; dew‑point and leak integrity continuously monitored.
- Scrap and chips from Nickel‑Iron Alloy Sheet are recyclable through certified channels.
📋 Procurement Checklist (Copy‑Paste)
When ordering 1J79 Permalloy Sheet, specify:
- Product form (sheet/plate/strip/foil) and thickness × width × length
- Required magnetic properties at test geometry (μi/μmax, Hc, Bs)
- Anneal condition (stress‑relief vs magnetic anneal)
- Surface finish (bright, Ra target) and coating (if any)
- Dimensional tolerances and flatness limits
- Inspection & MTR requirements (3.1 with test geometries)
- Packaging & labeling (export pack, barcodes)
- Any special handling or de‑gaussing instructions after fabrication
🧾 Typical Datasheet (Engineering Values)
Below is a consolidated datasheet for quick reference in design reviews. Values are typical; set contractual minima where needed.
General
- Alloy family: Ni‑Fe‑Mo soft magnetic
- Grade: 1J79 Permalloy Sheet / 1J79 Permalloy Plate
- Density: 8.7 g/cm³
- Electrical resistivity: 0.45–0.60 μΩ·m
- Curie temperature: ~450 °C
Magnetic (annealed)
- μi ≥ 15,000 (ring method)
- μmax ≥ 80,000 (post MA)
- Hc ≤ 2.0 A/m
- Bs ≥ 0.8 T
Mechanical (annealed)
- YS 0.2%: 200–300 MPa
- UTS: 400–550 MPa
- Elongation: 25–40%
- Hardness: HV 130–160
Process
- Stress‑relief anneal: 700–900 °C, 1–2 h
- Magnetic anneal: 1050–1200 °C, 2–4 h, H₂/Ar, slow cool ≤ 50 °C/h
- Recommended min bend radius: r ≥ 1.0×t (annealed)
🧠 Engineering FAQs
Q1. How do I guarantee the required permeability in my final parts?
A: Minimize cold‑work during fabrication, preserve clean surfaces, and request a final magnetic anneal. Measure μ on a geometry that approximates the part (ring/strip) and specify Hc/μ acceptance on your PO for 1J79 Permalloy Sheet.
Q2. Does higher thickness automatically yield better shielding?
A: Only up to the point where μ·t/D dominates; saturation and demagnetization effects limit gains. Multi‑layer shields of 1J79 Permalloy Sheet often outperform a single thick wall.
Q3. Can I weld after magnetic anneal?
A: Avoid it. If welding is necessary, perform it before MA and then re‑anneal. Otherwise HAZ will degrade permeability and increase Hc.
Q4. What if my application needs higher Bs?
A: Consider 1J50 or silicon steels for higher saturation, but expect lower μ and higher Hc than 1J79 Permalloy Sheet.
Q5. What standards apply?
A: Procurement against ASTM A753 classes for wrought Ni‑Fe soft magnets and measurement practices per IEC 60404 series are common for Nickel‑Iron Alloy Sheet.
🧷 Ordering Information & Lead Time
- MOQ: Flexible for development lots of 1J79 Permalloy Sheet and Soft Magnetic Alloy Sheet.
- Lead time: From stock for common gauges; made‑to‑order sizes subject to anneal queue and flattening schedules.
- Logistics: Global air/sea freight with export‑compliant packing; HS code available on request for 1J79 Permalloy Plate.
📞 Contact Us
📧 Email: sales@niticu.com
📞 Phone / WhatsApp / WeChat: +86 13335373172
🏭 Factory: Baotai Road Industrial Park, High‑tech Zone, Baoji City, Shaanxi, China
🌐 Website: https://niticu.com
For application reviews, data sheets, or samples of 1J79 Permalloy Sheet, reach out. Our engineers will optimize gauge, heat‑treatment, and shield geometry for your target field and size constraints.
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