Quick AnswerFeNi (50%Fe-50%Ni) and MPP (81%Ni-17%Fe-2%Mo) are both distributed-air-gap powder cores. MPP offers the lowest core loss and very stable permeability at low flux density, while FeNi provides a higher saturation flux density (Bs ≥1.5T vs ~0.75T) and stronger DC bias stability at high current, at a lower alloy cost. Choose MPP for loss-critical moderate-current filtering; choose FeNi for AI GPU VRM, server POL, EV charger and solar high-current power delivery.
FeNi and MPP are the two premium powder core families used when iron powder loss is too high and ferrite saturation is too low. Both are pressed from insulated alloy particles with a distributed air gap, but their compositions give them different strengths. This guide compares FeNi vs MPP on the properties that decide high-current inductor performance.
FeNi powder cores use a 50% iron – 50% nickel alloy, typically pressed to permeabilities of 14–160µ. MPP (Molybdenum Permalloy Powder) uses 81% nickel, 17% iron and 2% molybdenum, with permeabilities from 14µ up to 550µ. Higher nickel content gives MPP lower hysteresis loss but also a much higher raw-material cost.
This is the biggest practical difference. FeNi cores reach Bs ≥1.5T, while MPP saturates around 0.75T. In a 60–100A VRM phase or a high-current EV charger stage, the FeNi core carries the same current in significantly less volume because the operating flux stays further from saturation. That is why FeNi dominates AI GPU VRM and server POL power delivery.
MPP has the lowest core loss of the common powder cores, especially at low flux density and mid frequencies, which is why it remains the reference for precision filter inductors and output chokes. FeNi keeps core loss ≤300kW/m³ at 100kHz and stays efficient into the MHz range, with the gap narrowing at higher flux density where MPP approaches saturation.
Both families have a distributed air gap, so inductance rolls off gradually under DC bias instead of collapsing. FeNi maintains permeability variation ≤8% across −40°C to +180°C, keeping inductance predictable when load current swings hard. MPP is also stable, but its lower Bs forces a larger core when the same peak current must be supported.
FeNi operates reliably from −40°C to +180°C with flat temperature dependence, suiting automotive and outdoor energy equipment. MPP has a high Curie temperature and low loss drift as well, but the practical thermal advantage in high-current designs usually goes to FeNi because the smaller core runs cooler at the same current.
Nickel is the dominant cost driver. MPP’s 81% nickel content makes it the most expensive common powder core; FeNi at 50% nickel is cheaper per kilogram while still offering Bs ≥1.5T. For the same inductance at high current, FeNi also needs less core material, widening the cost gap.
| Property | FeNi (50Fe/50Ni) | MPP (81Ni/17Fe/2Mo) |
|---|---|---|
| Permeability | 14–160µ | 14–550µ |
| Saturation Bs | ≥ 1.5 T | ≈ 0.75 T |
| Core loss | Low (≤300kW/m³ @100kHz) | Lowest of powder cores |
| DC bias stability | Excellent (≤8% permeability drift) | Excellent |
| Temperature range | −40°C ~ +180°C | Wide (high Curie temp) |
| Relative cost | Moderate (50% Ni) | Highest (81% Ni) |
| Typical role | High-current power delivery | Loss-critical filtering |
YUTE Magnetics manufactures FeNi powder core inductors (YTFN series) and custom high-current magnetics with IATF 16949 and AEC-Q200 qualification. Send your frequency, current and loss targets for a free engineering evaluation.
See the High Flux Cores Guide, the Core Selection Guide and the DC Bias Considerations for AI GPU VRM for deeper design guidance.
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