What Alloys Are Magnetic?

In the world of metallurgy and material science, magnetism plays a crucial role in selecting materials for various industrial applications. From motors and transformers to sensors and shielding devices, magnetic properties are often a key performance requirement. But not all metals or alloys are magnetic, and the degree of magnetism can vary widely.

This article answers a common question: What alloys are magnetic? It provides a complete guide to magnetic alloy types, how magnetism works in metals, and where these materials are used. This comprehensive overview is brought to you by sasaalloy, a trusted supplier of specialty metals and alloys across global industries.

1. Understanding Magnetism in Alloys

Before diving into the list of magnetic alloys, it’s important to understand what magnetism means in metals:

• Ferromagnetism: Strongly magnetic. Materials like iron, cobalt, and nickel fall into this category. These metals retain magnetism even after the external magnetic field is removed.

• Paramagnetism: Weak and temporary attraction to a magnetic field, typically not noticeable without instruments.

• Diamagnetism: Weakly repelled by magnetic fields. This behavior is very weak and usually ignored in industrial applications.

Most magnetic alloys are ferromagnetic, meaning they exhibit strong magnetic properties due to the alignment of magnetic domains in the metal’s crystal structure.

2. Magnetic Base Metals

The three primary elements that are naturally magnetic and serve as the base for magnetic alloys are:

• Iron (Fe)

• Cobalt (Co)

• Nickel (Ni)

All magnetic alloys are based on these elements or combinations thereof. By adding other elements, manufacturers can control strength, temperature resistance, electrical properties, and corrosion resistance.

3. Common Magnetic Alloys

1. Iron-Based Alloys

Iron is the most magnetic of all metals and forms the basis for many magnetic materials.

a) Carbon Steel and Low Alloy Steel

• Contains mostly iron with small amounts of carbon and manganese

• Magnetic in nature

• Used in tools, construction, and machinery

b) Silicon Steel (Electrical Steel)

• Iron with 1–4% silicon

• Designed for low electrical losses and high magnetic permeability

• Common in transformers, motors, and generators

c) Stainless Steel (400-Series)

• Grades like 410, 430, and 446 are ferritic and magnetic

• Used in appliances, automotive trim, and industrial components

• Austenitic stainless steels like 304 and 316 are generally non-magnetic unless cold worked

2. Nickel-Based Magnetic Alloys

Nickel is inherently magnetic and is alloyed with iron or cobalt for enhanced performance.

a) Permalloy (Ni-Fe)

• Typically 80% nickel and 20% iron

• High magnetic permeability and low coercivity

• Used in magnetic shielding and transformers

b) Invar (Fe-Ni)

• 36% nickel, 64% iron

• Minimal thermal expansion, magnetic at room temperature

• Used in precision instruments and aerospace

c) Mu-metal

• Nickel-iron alloy with molybdenum and copper

• Extremely high permeability, used in magnetic shielding

• Very sensitive to heat and mechanical stress

d) Nickel-Cobalt Alloys

• Combines magnetic properties with strength and corrosion resistance

• Used in high-performance magnetic sensors and actuators

3. Cobalt-Based Magnetic Alloys

Cobalt is strongly magnetic and used where high temperature stability is required.

a) Alnico (Aluminum-Nickel-Cobalt)

• Contains aluminum, nickel, cobalt, and iron

• High magnetic strength and temperature resistance

• Used in loudspeakers, sensors, electric motors

b) Vicalloy (Fe-Co-V)

• Iron, cobalt, and vanadium

• Strong permanent magnet characteristics

• Used in precision sensors and instruments

c) Samarium-Cobalt (SmCo)

• Rare earth + cobalt alloy

• Excellent temperature stability and corrosion resistance

• High-energy permanent magnets used in aerospace and medical devices

4. Properties of Magnetic Alloys

Different magnetic alloys offer specific performance features depending on their composition:

• Magnetic Permeability: Ability to support magnetic field lines. High in materials like Permalloy.

• Coercivity: Resistance to becoming demagnetized. Low in soft magnets, high in hard magnets.

• Saturation Magnetization: The maximum magnetic strength of the material.

• Curie Temperature: The temperature above which a material loses its magnetism.

These characteristics are critical when selecting materials for electric motors, inductors, or magnetic shielding.

5. Applications of Magnetic Alloys

Due to their unique properties, magnetic alloys are widely used in:

1. Electrical and Power Equipment

• Transformer cores (silicon steel)

• Magnetic sensors and relays

• Electric motor laminations

2. Magnetic Shielding

• Mu-metal and Permalloy used to shield sensitive electronics from external magnetic interference

• Found in MRI machines, aerospace components, and defense systems

3. Permanent Magnets

• Alnico, Samarium-Cobalt, and Neodymium magnets used in:

  • Wind turbines

  • Microphones and loudspeakers

  • Hard disk drives

4. Precision Instruments

• Invar and Vicalloy used in timekeeping devices, instruments, and navigation systems

• Maintain magnetic stability over temperature changes

sasaalloy provides a wide range of magnetic alloys customized for these high-performance environments.

6. Magnetic vs Non-Magnetic Alloys

7. How to Test If an Alloy Is Magnetic

There are several simple and advanced methods:

• Magnet Test: Use a permanent magnet to see if the material is attracted.

• Hall Effect Sensor: Measures magnetic field strength.

• Gaussmeter: Measures magnetic flux density.

• Magnetic Permeability Meter: Measures the ease of magnetization.

When sourcing or verifying materials, testing is essential to ensure compliance with magnetic performance requirements.

8. Factors That Affect Magnetism in Alloys

• Heat Treatment: Annealing or hardening can alter magnetic properties.

• Cold Working: Can induce magnetism in non-magnetic grades like 304 stainless steel.

• Impurities: Small amounts of non-magnetic elements can weaken magnetism.

• Mechanical Stress: Distortion can reduce magnetic alignment in shielding materials.

sasaalloy ensures precise control over composition and processing to deliver consistent magnetic performance in every product.

9. Why Choose Magnetic Alloys from sasaalloy

At sasaalloy, we specialize in magnetic materials for advanced industrial and scientific applications. Our products offer:

• High magnetic permeability or strong permanent magnetism

• Precise chemical compositions and metallurgical control

• Available in wire, strip, rod, sheet, and custom forms

• Support for high-temperature and corrosive environments

Whether you’re developing a motor, shielding sensitive electronics, or fabricating medical devices, sasaalloy provides reliable solutions with technical support to match.

10. Conclusion: What Alloys Are Magnetic?

In conclusion, magnetic alloys are primarily based on iron, cobalt, and nickel, often enhanced with other elements to meet specific industrial needs. Alloys like silicon steel, Alnico, Permalloy, Mu-metal, and Samarium-Cobalt are widely used in electrical systems, sensors, permanent magnets, and shielding.

Yes, not all metals are magnetic, but the right alloy can deliver powerful, precise magnetic performance across a wide range of industries. Understanding the composition, structure, and treatment of magnetic alloys allows engineers and manufacturers to choose the best materials for each application.