Alloy 79 Soft Magnetic Alloy,Magnifer 7904, HyMu 80, Hipernom, Moly-Permalloy, Permalloy 80.ASTM A753, MIL N-14411C,E FORU

### **Alloy 79 (Moly-Permalloy®) - High Permeability Nickel-Iron Soft Magnetic Alloy** #### **Overview** **Alloy 79**, also known by its common trade names **Moly-Permalloy**, **HyMu 80**, **Hipernom**, and **Permalloy 80**, is a high-performance, nickel-iron soft magnetic alloy containing approximately 80% nickel and a critical addition of 4-5% molybdenum. It is part of the Permalloy family and is specifically engineered to exhibit an extremely high magnetic permeability, very low coercivity, and a sharp magnetic saturation characteristic. The addition of molybdenum significantly enhances the alloy's electrical resistivity compared to the simpler 80% nickel Permalloy, which reduces eddy current losses, making it superior for AC applications. It is typically supplied in a soft, ductile, annealed condition and achieves its optimal magnetic properties after a final heat treatment in a protective or dry hydrogen atmosphere. --- #### **Chemical Composition (Weight % - Typical)** The composition is tightly controlled to achieve the desired magnetic softness. | Element | Content (%) | | :--- | :--- | | **Nickel (Ni)** | **78.0 - 81.0** | | **Molybdenum (Mo)** | **4.0 - 5.0** | | **Iron (Fe)** | **Balance** | | **Manganese (Mn)** | **0.50 - 1.50** | | **Silicon (Si)** | **≤ 0.30** | | **Carbon (C)** | **≤ 0.03** | | **Sulfur (S)** | **≤ 0.02** | * **Nickel (Ni):** The primary element, responsible for achieving high initial permeability and a low magnetostriction coefficient. * **Molybdenum (Mo):** The key additive that increases electrical resistivity and enhances the alloy's workability and hardness. It also contributes to achieving the highest permeabilities. * **Manganese (Mn):** Acts as a deoxidizer during melting. * **Low Carbon & Sulfur:** Essential for magnetic softness, as interstitial elements like carbon and sulfur can pin magnetic domains, increasing coercivity and hysteresis losses. --- #### **Physical & Magnetic Properties** The following table outlines the key physical and magnetic properties of Alloy 79 in the annealed condition. | Property | Value / Description | | :--- | :--- | | **Density** | 8.74 g/cm³ | | **Curie Temperature** | ~460 °C (860 °F) | | **Electrical Resistivity** | ~58 μΩ·cm | | **Saturation Induction (Bsat)** | ~0.75 - 0.82 T (7500 - 8200 Gauss) | | **Initial Permeability (μi)** | **20,000 - 35,000** (typical, at 0.002 T) | | **Maximum Permeability (μmax)** | **100,000 - 200,000** (typical) | | **Coercivity (Hc)** | **< 0.5 - 2.0 A/m** (Very low) | | **Saturation Magnetostriction** | ~2 x 10⁻⁶ (Very low) | *Note: Actual magnetic properties are highly dependent on final heat treatment, cold work reduction, and the strength of the magnetic field applied.* --- #### **Key Characteristics & Applications** **Key Characteristics:** 1. **Extremely High Magnetic Permeability:** Allows for easy magnetization and demagnetization, making it highly efficient for concentrating magnetic flux. 2. **Very Low Coercive Force (Hc):** Results in very narrow hysteresis loops, meaning very low energy loss per AC cycle. 3. **Low Core Losses:** The combination of high resistivity and low hysteresis loss makes it efficient for high-frequency operation. 4. **Low Magnetostriction:** Minimizes dimensional changes during magnetization, which is critical for stable performance in sensitive devices. 5. **High Flux Density at Low Field Strengths:** Saturates with a relatively small applied magnetic field. **Typical Applications:** Alloy 79 is used in a wide range of sensitive electronic and electrical components where high magnetic efficiency is critical. * **Magnetic Shielding:** The premier material for sensitive equipment like CRT displays, photomultiplier tubes, MRI systems, and satellite components to protect against external magnetic fields. * **Transformers & Inductors:** Used in high-permeability, low-loss cores for audio frequency transformers, pulse transformers, and precision inductors. * **Telecommunications:** Components in loading coils, filters, and miniature magnetic components for telecommunication circuits. * **Sensors & Transducers:** Used in flux gates, magnetometers, and other magnetic field sensing devices. * **Recording Heads:** Historically used in magnetic tape and disk recording heads. --- #### **International Standards** Alloy 79 is covered by several key international and military specifications. | Standard / Specification | Designation / Type | Description | | :--- | :--- | :--- | | **ASTM A753** | **Type 4** | This is the primary ASTM standard for "Wrought Nickel-Iron Soft Magnetic Alloys." Alloy 79 (80Ni-4Mo-Fe) is classified under **Type 4**. | | **MIL-N-14411C [Superseded but referenced]** | **Composition 1** | This U.S. military specification defined "Nickel-Iron Soft Magnetic Alloys." Alloy 79 falls under Composition 1. It is often referenced in legacy designs and some procurement documents. | | **UNS Number** | **K94890** | The Unified Numbering System identifier for this alloy composition. | | **Trade Names** | **HyMu 80®** (Carpenter Technology)
**Moly-Permalloy®**
**Hipernom®**
**Magnifer 7904** | Various manufacturers produce this alloy under proprietary trade names. The underlying composition and properties are fundamentally equivalent. | --- #### **Summary** In summary, **Alloy 79 (Moly-Permalloy)** is a premier soft magnetic material renowned for its extremely high permeability and low core losses. Its optimized composition, featuring 80% nickel and 4-5% molybdenum, makes it the material of choice for demanding applications in magnetic shielding, high-performance transformers, and sensitive sensors. Governed by standards like **ASTM A753 Type 4** and historically by **MIL-N-14411C**, it remains a benchmark for high-permeability nickel-iron alloys in both commercial and defense-related electronics.

Packing of Standard Packing: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3207 gallon liquid totes Special package is available on request.