Transmart - Professional Transformer Core Manufacturers In China Supplying Custom Nanocrystalline Core And Toroidal Transformer Core

What Is a Nanocrystalline Core and How Is It Made?

2026-09-11

A transformer at 100kHz shouldn't lose energy the way a 50Hz one does. A lot of them still do, though, someone picked the wrong core material for the job. Ferrite saturates too fast. Silicon steel heats up once you push the frequency higher. That's the whole reason nanocrystalline cores left the lab and started showing up everywhere, EV chargers, renewable energy setups, power electronics, over the last ten years or so.

This article covers what the material actually is, and why engineers keep choosing it over ferrite and amorphous cores instead. Real data backs all of it here, not marketing claims.

What Is a Nanocrystalline Core?

A nanocrystalline magnetic core uses this fine grain structure to achieve high permeability and low magnetic losses. It's a soft magnetic part, made from iron mixed with a bit of silicon, boron, niobium, and copper. But honestly, it's not really about which elements go in. It's the grain structure that matters. Silicon steel has big, rough grains. This stuff has tiny grains, 10 to 20 nanometers, sitting in leftover amorphous material.

That grain size is basically everything. It's why the material does what it does:

Permeability that can hit 20,000 to 100,000 at 10kHz, depends on the alloy and how it's heat treated
Demagnetizes easily, so you lose less energy to hysteresis
Saturates around 1.2 Tesla, way better than ferrite
Barely any magnetostriction, so less noise, less mechanical stress on the core

You might see it called a FINEMET-type alloy sometimes. That's just a brand thing though, "nanocrystalline" is really just about the grain structure, nothing to do with who makes it.

Nanocrystalline Cores For Current Transformers

How Is a Nanocrystalline Core Made?

The manufacturing process determines the final properties of the nanocrystalline magnetic core, so each stage needs careful control. Producing this material is not a single-step casting process. It runs through several controlled stages, and skipping or rushing any one of them changes the final magnetic performance.

1. Melting and Alloying

They begin with a mix of iron that has just the right amounts of silicon, boron, niobium, and copper, which they carefully melt in a furnace. The mix of ingredients aren't accidental - niobium and copper are "grain refiners," which means small variations to even the quantities added of the elements will result in different grain fineness.

2. Rapid Solidification

The molten mix of materials isn't let cool normally, rather it cools really, via a "melt spinning" process, a stream of liquid metal poured onto a high-speed rotating wheel. Cooling occurs at a rate so fast that the individual iron molecules don't have time to group together to form sizable crystals. You're left with a super thin ribbon of an amorphous solid, usually 15 - 25 micrometers in size. This amorphous material doesn't have its nanocrystal structure yet; that will come in the next stage of manufacturing.

3. Heat Treatment and Annealing

This is the key process where the amorphous ribbon becomes nanocrystalline. The amorphous ribbons are subjected to a carefully controlled annealing (or heat treatment) process, around 500-600C for an amount of time that is specific to a given batch of materials. The heat treatment process starts some crystallisation, but because of the copper, Nb, and the amount of time/temp involved, there's nowhere near enough time for atoms to make huge crystals.

4. Core Formation and Winding

Once the ribbon has its final magnetic properties, it is wound into shape. Toroidal cores are wound continuously around a mandrel, while cut cores and C cores are formed by winding, then precision-cutting the ribbon stack. The winding tension and layer count both affect the finished core's inductance and mechanical stability.

5. Coating, Insulation, and Encapsulation

This layer of ribbon is not only thin but glassy in the first place, and that's why final cores get varnish/epoxy. Therefore, in most cases, packaged into a steel or plastic frame to protect from liquid or mechanical effects and also to prevent eddy current losses in layers.

Nanocrystalline Core Toroidal Core

Why Nanocrystalline Cores Outperform Ferrite and Amorphous Alternatives

Engineers don't make a core material decision from a single parameter, and here's a compilation of the 3 most frequently used types of soft magnetic cores, with well-known magnetic properties.

Property	Nanocrystalline Core	Amorphous Core (Fe-based)	Ferrite Core (Mn-Zn)
Saturation flux density	1.2 to 1.25 T	1.5 to 1.56 T	0.3 to 0.5 T
Initial permeability	80,000 to 150,000	3,000 to 8,000	1,000 to 10,000
Coercive force	0.3 to 1.5 A/m	1 to 4 A/m	10 to 100 A/m
Curie temperature	560 to 570°C	400 to 410°C	200 to 250°C
Resistivity	130 μΩ·cm	130 to 150 μΩ·cm	10² to 10⁴ μΩ·cm
Typical iron loss at 10 kHz, 0.5 T	8 to 12 W/kg	30 to 45 W/kg	Fails at 0.5 T
Applicable frequency range	50 Hz to 150 kHz	50 Hz to 20 kHz	1 kHz to 1 MHz
Temperature range	−40 to 180°C	−40 to 150°C	−20 to 120°C

Why Demand for Nanocrystalline Cores Keeps Growing

The following are just some estimates of growth in this market by leading, independent market research agencies:

In a 2026 report, 360iResearch placed the global nanocrystalline core market size at 1.47 billion dollars in 2025 and is projected to hit 2.49 billion dollars by 2032, at a compound annual growth rate (CAGR) of 7.83%.
According to Spherical Insights, the world's nanocrystalline soft magnetic materials market will rise from 2.81 billion dollars in 2025 to 5.93 billion dollars in 2035 at a CAGR of 7.75%.
And Lucintel reported the overall amorphous and nanocrystalline core market would be valued at 1.9 billion dollars by 2035, driven primarily by new energy-efficient power infrastructure, increased data-center demand, as well as renewable energy initiatives and installations.

The common thread across all three reports is the same: as power electronics push toward higher switching frequencies and higher power density, ferrite starts to run out of headroom, and nanocrystalline cores become the practical upgrade path.

Nanocrystalline Cores EMC Common Mode Choke Core

Where Nanocrystalline Cores Are Actually Used

The properties of a nanocrystalline magnetic core make it useful in several power and magnetic applications where low loss and high permeability matter. The material shows up across a wide range of equipment, though not every application calls for the same core geometry:

Common mode chokes, where high permeability suppresses EMI noise on power lines. Transmart's common mode choke cores are built specifically for this role in converters and inverters.
Current transformers, where measurement accuracy depends on low core loss and stable permeability. See Transmart's current transformer cores for this application.
High-power transformers, where thermal stability at sustained load matters more than raw saturation. Transmart's nanocrystalline cores for high-power transformers are designed around this requirement.
Cut cores and gapped cores, used where a controlled air gap is needed to set a specific inductance, such as Transmart's nanocrystalline split core and gap core line.
Block and custom-shaped cores, for equipment with unusual mounting or space constraints, are covered under Transmart's custom nanocrystalline block cores.

Conclusion

Not every manufacturer controls the full production chain from melting through annealing, and that gap shows up in the finished core's consistency. Before committing to a supplier, it helps to check:

Whether the annealing process is documented and repeatable batch to batch, not just a general spec sheet claim
Whether the supplier provides a full technical data sheet, including permeability curves and core loss figures at your actual operating frequency
Whether they offer both standard toroidal geometries and custom shapes for space-constrained designs
Whether their production supports the pin configuration, mounting style, and encapsulation your application actually needs

Transmart's technical data resources and broader nanocrystalline core product range are built around giving engineers this kind of documentation up front rather than after the order is placed.

Frequently Asked Questions

1.Is the nanocrystalline core and amorphous core the same?

No. They both use the quenched ribbon material. Nanocrystalline cores are subsequently annealed after quenching to get the tiny grains.

2.How can the loss of the nanocrystalline core remain relatively low at high frequency?

Because the material ribbon is extremely thi,n, preventing eddy currents from becoming a factor of escalating size as frequency increases.

3.Can the ferrite core in my application be substituted by a nanocrystalline core for any design?

No. Ferrite can achieve relatively good results in those applications. For example, fundamental EMI filtering as well as applications at lower frequencies.

4.How much temperature can nanocrystalline cores sustain?

Several types of nanocrystalline alloys possess Curie points of 550- 570 °C. Generally operation temperature may be much lower than these values and relates to the construction of the cores.