What Metals Are Magnetic: Essential Guide to Magnetism in Metals
Only a few metals—iron, nickel...
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Only a few metals—iron, nickel, and cobalt—are truly magnetic because their atoms align in a way that creates astrong magnetic field. These ferromagnetic metals attract magnets and can become magnets themselves. Alloys that include these elements, such as certain types of steel, also show strongmagnetic behavior.
Magnetism in metals depends on how electrons move and align inside atoms. When unpaired electrons spin in the same direction, they create a magnetic field that can interact with others. This property explains why some metals, like copper or aluminum, stay non-magnetic even though they conduct electricity well.
This article explains how magnetism works in metals, the types of magnetic and non-magnetic metals, and where these materials are used. It draws on research from materials science and engineering to give practical insights into how magnetic metals shape industries such as electronics, construction, and manufacturing.
How Magnetism Works in Metals
Magnetism in metals arises from the behavior of electrons and how their magnetic moments align within a material. The strength and stability of this magnetism depend on atomic structure, domain alignment, and temperature limits that affect electron spin orientation.
Role of Electrons and Atomic Structure
Each metal atom contains electrons that move around the nucleus and spin on their axes. This spin generates a magnetic moment of about 9.27 × 10⁻²⁴ A·m² (the Bohr magneton). In ferromagnetic metals such as iron (Fe, atomic number 26), nickel (Ni, 28), and cobalt (Co, 27), unpaired 3d electrons create a net magnetic moment because their spins align in the same direction.
The body-centered cubic (BCC) structure of α-iron allows magnetic moments to align easily, resulting inhigh magnetic permeability of up to 5,000 relative μr. In contrast, the face-centered cubic (FCC) structure of γ-iron disrupts alignment, making it nonmagnetic. Nickel’s FCC lattice still supports ferromagnetism because its electron configuration (3d⁸ 4s²) leaves unpaired spins that interact strongly.
When an external magnetic field of around 0.1 to 1 Tesla is applied, these spins align more fully, increasing magnetization. Once the field is removed, the degree of retained alignment—known as remanence—depends on the metal’s crystalline structure and electron exchange energy, typically 0.3 to 1 eV per atom.
Magnetic Domains and Magnetic Moments
Inside ferromagnetic metals, atoms group into magnetic domains—regions about 1 to 100 micrometers wide where magnetic moments point uniformly. In an unmagnetized sample, these domains are randomly oriented, so their fields cancel. When magnetized, domain walls shift, aligning domains along the applied field direction.
The total magnetization (M) is the sum of all domain moments per unit volume, often reaching 1.6 × 10⁶ A/m for pure iron. This alignment creates a measurable external field of roughly 2 Tesla in high-grade magnetic steel. Because cobalt maintains order up to 1,120°C (Curie temperature), it retains magnetism better than iron, which loses it above 770°C.
Domain wall motion depends on impurities and grain boundaries. Soft magnetic materials like silicon steel (Fe–Si 3%) have low coercivity (<100 A/m), allowing easy magnetization and demagnetization. Hard magnetic materials such as Nd₂Fe₁₄B resist domain reversal, requiring fields above 800 kA/m to demagnetize. This property makes them suitable for permanent magnets in motors, sensors, and generators.
Types of Magnetic Metals and Alloys
Magnetic metals and alloys differ in how their atoms align when exposed to a magnetic field. Some can becomepermanent magnets, while others show only weak attraction or repulsion. Their behavior depends on crystal structure, temperature limits, and electron configuration.
Ferromagnetic Metals: The Most Common Magnets
Ferromagnetic metals have strong magnetic domains that align in the same direction when exposed to a magnetic field. This alignment allows them to retain magnetization even after the field is removed.
Iron (Fe) displays a magnetic saturation of about 2.2 tesla (T) and a Curie temperature of 770 °C. Because of this, it is used in transformer cores and electric motor stators. Its body-centered cubic structure supports stable domain formation, which explains its ability to hold magnetism.
Nickel (Ni) has a magnetic saturation near 0.6 T and a Curie temperature of 358 °C. It resists corrosion and is often applied as a plating layer on steel components. Its face-centered cubic structure produces moderate magnetic retention, which suits it for electronic connectors and sensors.
Cobalt (Co) maintains magnetism up to 1,121 °C, making it suitable for aerospace andhigh-temperature magnets. In alloys, cobalt improves coercivity, meaning the magnet resists demagnetization.
Rare earth metals such as neodymium (Nd), samarium (Sm), and gadolinium (Gd) form compounds like Nd₂Fe₁₄B and SmCo₅. These materials reach magnetic energy products above 400 kJ/m³, allowing compact motors and data storage devices to operate efficiently.
Common Magnetic Alloys
Magnetic alloys combine metals to balance strength, temperature stability, and corrosion resistance.
Steel, mainly iron with up to 2% carbon, is ferromagnetic in ferritic and martensitic forms. When alloyed with chromium and nickel, as in stainless steel, its magnetism changes. Ferritic stainless steel (grade 430) remains magnetic due to its body-centered cubic structure, while austenitic stainless steel (grade 304) is mostly nonmagnetic because of its face-centered cubic lattice.
Alnico, composed of 8–12% aluminum, 15–26% nickel, and 5–35% cobalt, reaches a magnetic energy product around 10 kJ/m³. It works in instruments and loudspeakers where temperature stability up to 540 °C is needed.
Permalloy, a Ni–Fe alloy containing about 80% nickel, offers high magnetic permeability (μr ≈ 100,000).
Because it magnetizes and demagnetizes easily, engineers use it in transformer cores and magnetic shielding.
Ferrite alloys, made from iron oxide and other metals like manganese or zinc, are ceramic-based and resist corrosion. Their saturation flux density of 0.3–0.5 T suits them for low-frequency transformers and inductors.
Other Types of Magnetism
Not all metals show strong or permanent magnetism. Some interact weakly with magnetic fields but still have practical uses.
Ferrimagnetic materials such as magnetite (Fe₃O₄) have opposing magnetic sublattices with unequal strengths, resulting in a net magnetization of about 0.48 T. They are used in magnetic recording and microwave components because they maintain magnetism without high electrical conductivity.
Paramagnetic metals like aluminum, magnesium, and lithium have unpaired electrons that align weakly with magnetic fields. Their magnetic susceptibility is small and positive, around 10⁻⁵, meaning they lose magnetization once the external field disappears.
Diamagnetic metals such as copper, silver, and gold have all electrons paired, giving them a negative susceptibility near −10⁻⁵. This causes slight repulsion from magnets. Though weak, this property benefits precision instruments that require minimal magnetic interference.
Applications and Uses of Magnetic Metals
Magnetic metals enable energy conversion, motion control, and data detection in many technologies. They serve as the foundation for magnets, electric machines, and precision medical tools that rely on magnetic fields for accurate and efficient operation.
Magnets and Magnetic Devices
Permanent magnets made from NdFeB (neodymium-iron-boron) alloys reach magnetic energy densities up to 400 kJ/m³, allowing compact designs for speakers, sensors, and motors. Samarium-cobalt (SmCo) magnets operate at temperatures up to 350°C, making them suitable for aerospace and defense systems.
Soft magnetic materials like silicon steel (Fe–3%Si) show low coercivity below 100 A/m, reducing energy loss in transformers and inductors. Because of their high permeability (μr ≈ 2,000–8,000), they allow efficient magnetic flux transfer with minimal heat generation.
Electromagnets use an electric current through copper windings to create adjustable magnetic fields. When powered at 12 V DC and 2 A, a coil can generate a field of about 0.1 T, which can be turned off instantly—unlike permanent magnets. This controllability makes them essential in cranes, relays, and magnetic locks.
Temporary magnets, such as magnetized iron bars, lose magnetism once the external field is removed. They are used in training tools and low-cost holding devices where reversibility is required.
Electric Motors and Generators
Electric motors and generators rely on magnetic metals to convert between electrical and mechanical energy.
Stator cores typically use laminated electrical steel sheets of 0.35 mm thickness to reduce eddy current loss by up to 85% compared to solid cores.
In interior permanent magnet (IPM) motors, neodymium magnets embedded in the rotor provide high torque density, reaching 3.5 Nm/kg. Because the magnets maintain strong flux at temperatures below 150°C, they improve efficiency in electric vehicles and industrial drives.
Generators use similar magnetic principles but operate in reverse. When a rotor spins within a magnetic field, it induces voltage in the stator coils. High-grade Fe–Ni (80:20) alloys with magnetic permeability above 10,000 H/m ensure stable output for wind turbines and hydroelectric systems.
Trade-offs arise between magnetic strength and cost. Rare-earth magnets deliver compact performance but depend on limited materials, while ferrite magnets offer lower flux density (~0.4 T) but better affordability and corrosion resistance.
Medical and Industrial Applications
Magnetic metals play critical roles in imaging, separation, and detection. MRI (Magnetic Resonance Imaging) machines rely on superconducting electromagnets cooled with liquid helium at 4 K, producing fields up to 3 T. The magnetic uniformity within ±0.001 T ensures accurate tissue imaging.
In metal detectors, oscillating electromagnetic fields detect conductive or ferromagnetic objects by measuring changes in coil impedance. Typical handheld detectors operate at 7–20 kHz, optimized for detecting small iron or nickel fragments in food and construction materials.
Industrial separators use ferrite or NdFeB magnets arranged in grids or drums to remove ferrous contaminants from powders and liquids. Magnetic field strengths of 0.2–1.2 T enable continuous operation in mining and recycling systems. Because of their corrosion-resistant coatings (Ni–Cu–Ni, 20 µm thick), these magnets maintain performance under humid or abrasive conditions.
Transportation and Emerging Technologies
Magnetic metals drive innovation in electric and automated transport. Electric vehicle (EV) motors commonly use neodymium magnets with coercivity above 900 kA/m, enabling compact motors that reach 95% efficiency. Because neodymium magnets retain magnetization up to 180°C, they support high-speed operation without demagnetization.
Magnetic levitation (maglev) trains use superconducting magnets cooled with liquid nitrogen at 77 K to create lift forces exceeding 5 kN/m. This eliminates wheel friction, allowing speeds above 500 km/h.
In transformers for charging infrastructure, laminated silicon steel cores minimize core loss to below 1.2 W/kg at 50 Hz, improving grid efficiency.
Emerging technologies include inductive charging pads that use ferrite-backed copper coils to transfer power wirelessly at 85 kHz. Because ferrite cores confine magnetic flux, they reduce stray fields and improve energy transfer efficiency to 93%. These developments show how magnetic metals continue to shape modern transportation systems and energy networks.
Non-Magnetic and Weakly Magnetic Metals
Most metals do not show strong magnetic attraction. Their atoms have paired electrons that cancel magnetic moments, making them either non-magnetic or weakly magnetic. These materials are chosen when magnetic interference must be avoided, such as in medical or electronic environments.
Common Non-Magnetic Metals
Non-magnetic metals include aluminum (Al), copper (Cu), gold (Au), silver (Ag), zinc (Zn), lead (Pb), brass, and titanium (Ti). Each has distinct electrical, thermal, and mechanical properties.
Aluminum has a density of 2.70 g/cm³ and melting point of 660°C, making it light and corrosion-resistant. Copper, with electrical conductivity of 5.96 × 10⁷ S/m, is used in wiring because its diamagnetism prevents signal distortion.
Gold and silver are both diamagnetic and resist oxidation, which is why they are used in electronics and jewelry. Lead, with a density of 11.34 g/cm³, provides radiation shielding where magnetism must remain neutral. Brass, an alloy of copper and zinc, combines corrosion resistance with low magnetic permeability (<1.001).
Paramagnetic and Diamagnetic Metals
Paramagnetic metals such as titanium, magnesium, and aluminum have unpaired electrons that align weakly with external magnetic fields. Their magnetic susceptibility ranges between 10⁻⁵ and 10⁻⁶ (SI units).
This weak attraction disappears once the field is removed because the domains do not align permanently.
Diamagnetic metals like copper, gold, silver, and bismuth create small opposing magnetic fields when exposed to magnets. Their susceptibility is negative, typically around −10⁻⁵, meaning they are slightly repelled.
Because their electron orbits generate opposing currents, they remain stable in high-precision instruments and MRI-safe environments.
These metals are selected for electronic connectors, medical implants, and non-magnetic housings where magnetic neutrality prevents interference or hazards.
Factors Affecting Magnetism in Metals
A metal’s magnetism depends on electron configuration, crystal structure, and temperature. Metals with unpaired 3d or 4f electrons, like iron, show ferromagnetism, while those with fully filled shells, such as copper or zinc, do not.
Crystal structures like face-centered cubic (FCC) reduce magnetic alignment, resulting in non-magnetic behavior. Austenitic stainless steels (types 304 and 316) are non-magnetic because their FCC structure prevents domain alignment.
Temperature also influences magnetism. Above the Curie temperature (e.g., 770°C for iron), even ferromagnetic metals become paramagnetic. Mechanical deformation, such as cold working, can induce slight magnetism in otherwise non-magnetic alloys by altering their grain structure and electron orientation.
Frequently Asked Questions
Some metals such as iron, cobalt, and nickel show strong magnetic attraction due to their ferromagnetic structure. Others, like certain stainless steels or precious metals, resist magnetism because of their atomic arrangement and electron spin. Temperature also changes how magnetic domains align, which can cause a metal to lose or regain magnetism.
Which types of steel are magnetic?
Steel becomes magnetic when its crystal structure is ferritic or martensitic, both of which have a body-centered cubic (BCC) lattice. This structure allows unpaired electrons in iron atoms to align easily, creating a ferromagnetic effect.
Ferritic stainless steels, such as Type 430, contain about 16–18% chromium and almost no nickel. Because of this composition, they retain the BCC structure and remain magnetic up to their Curie temperature of around 770°C.
In contrast, austenitic stainless steels like Type 304 or Type 316 have a face-centered cubic (FCC) lattice stabilized by 8–10% nickel. This structure prevents alignment of magnetic domains, making them non-magnetic unless cold-worked. When bent or stretched, partial transformation to a martensitic phase can restore some magnetism.
Are precious metals used in jewelry typically magnetic?
Precious metals such as gold (Au), silver (Ag), and platinum (Pt) are classified as diamagnetic. This means they weakly repel magnetic fields because all their electrons are paired, leaving no net magnetic moment.
Pure gold and silver have atomic numbers 79 and 47, respectively, and display magnetic susceptibility values around −3.4 × 10⁻⁶ (SI units). Platinum shows slightly higher susceptibility at −2.0 × 10⁻⁶, but it still does not attract magnets under normal conditions.
Jewelry alloys that include metals like nickel or iron can show weak magnetism. For example, white gold containing up to 10% nickel may respond faintly to a magnet, while platinum alloys with cobalt (5%) used in industrial applications can become slightly magnetic.
Can a metal's magnetic properties change with temperature?
Yes. Magnetic behavior depends strongly on temperature because heat affects the alignment of magnetic domains. Each ferromagnetic metal has a specific Curie temperature (Tc) where it loses its magnetism.
For iron, Tc is about 770°C; for nickel, it is 358°C; and for cobalt, it is 1,115°C. Above these points, thermal energy disrupts electron spin alignment, turning the material paramagnetic, meaning it is only weakly attracted to magnets.
When cooled below Tc, the domains realign spontaneously, restoring magnetism. This reversible process is used in devices likemagnetic sensors and temperature-controlled actuators, where predictable changes in magnetism allow precise control.
