HyMu 80 is an 80% nickel-iron-molybdenum soft magnetic alloy designed for applications requiring maximum magnetic permeability and minimal coercive force. It provides exceptionally high initial and maximum permeability, low hysteresis loss, and near-zero magnetostriction, making it the industry standard for magnetic shielding and high-performance transformer cores.

1. Operating Limits & Selection Criteria

This alloy is selected based on magnetic performance requirements rather than mechanical strength.

• Magnetic Performance: Provides initial permeability (μ₀) of 20,000-30,000 and maximum permeability (μ_max) exceeding 100,000 when properly annealed. Significantly higher than silicon steels or 50% nickel alloys.

• Effective Field Range: Optimized for low to moderate flux densities. Saturation induction is approximately 0.75 Tesla (7500 Gauss), lower than silicon steels. Not suitable for high-flux power applications above saturation.

• Frequency Range: Primarily for DC and low-frequency AC applications (up to a few kHz). For higher frequencies, thinner laminations or alternative materials may be required due to eddy current losses.

• Composition Variants: Two common specifications exist:

  • Standard HyMu 80 (Mo-Ni-Fe): Highest permeability, for critical shielding and precision components.

  • MIL-N-14411C Composition: Contains copper and chromium for specific corrosion resistance requirements, with slightly different magnetic characteristics.

2. Manufacturing Data & Specifications

• Chemical Composition (Typical)

  Element	HyMu 80 (Standard)	MIL-N-14411C
  Nickel (Ni)	79.0 - 80.6	75.0 - 77.0
  Molybdenum (Mo)	3.8 - 5.0	—
  Copper (Cu)	—	4.0 - 6.0
  Chromium (Cr)	—	3.0 max
  Manganese (Mn)	0.95	1.8
  Silicon (Si)	0.42	0.50 max
  Carbon (C)	0.03	0.05 max
  Iron (Fe)	Balance	Balance
  Sulfur (S)	0.008	0.02 max
  Phosphorus (P)	0.02	0.02 max

• Physical Properties

  Property	Metric	Imperial
  Density	8.74 g/cm³	0.316 lb/in³
  Curie Temperature	460°C	860°F
  Saturation Induction	0.75 T	7500 G

• Mechanical Properties (Annealed)

  Property	Metric	Imperial
  Tensile Strength	690 MPa	100,000 psi
  Yield Strength	300 MPa	44,000 psi
  Elongation in 2"	40%	40%
  Hardness	85 HRB	85 HRB

• Critical Fabrication Requirement: Final Annealing

  • Hydrogen Annealing: Magnetic properties are only developed through a high-temperature final anneal in dry hydrogen atmosphere.

  • Annealing Cycle: Typically 1175°C (2150°F) for 2-4 hours, followed by controlled cooling.

  • Stress Relief: Any mechanical processing (cutting, stamping, forming) after final anneal will degrade magnetic properties. Components should be fabricated first, then annealed. If post-anneal forming is required, a low-temperature stress relief (650-750°C) may partially restore properties but will not achieve full permeability.

3. Applications

HyMu 80 is specified wherever low-level magnetic fields must be contained or excluded:

• Magnetic Shielding: CRT shields, MRI room shielding, electron microscope enclosures, sensitive instrumentation

• Transformer Cores: Current transformers, high-permeability toroids, pulse transformers

• Magnetic Amplifiers: Saturable reactors and magnetic modulators

• Sensors: Fluxgate magnetometers, magnetic field detectors

• Audio: Recording head shields, high-end transformer laminations

• Medical: Shielding for pacemakers, implantable devices during manufacturing and storage

4. Available Product Forms & Supply

For engineers and procurement specialists requiring high-permeability magnetic alloys for shielding and precision magnetic components, ZYTC Alloy stocks certified HyMu 80 (1J79 / MuMetal 80) in multiple forms:

• Sheet & Strip (various thicknesses)

• Bar & Rod

• Tube

All material is supplied with full traceability and certification, suitable for aerospace, medical, electronics, and defense applications. Contact ZYTC Alloy for stock availability and pricing.

Email: daisy@zytcsteel.com

WhatsApp/WeChat: +86 17335753350