Every time you turn on a radio receiver, charge a smartphone, or watch a clear MRI image — somewhere inside the device a metal is working that can sense a magnetic field. It responds to the slightest fluctuations, amplifies them, directs them, or suppresses them.
This metal is a nickel-based soft magnetic alloy. It does not merely conduct current or hold shape; it controls invisible flows of magnetic energy, creating the foundation of modern electronics and instrumentation.
In this article we will become acquainted with these unique materials — their chemical composition, structure, and properties.
Imagine a metal that responds to the slightest magnetic pulse the way a tuner locks onto the needed frequency. That is how soft magnetic materials behave — they magnetize easily and just as easily return to the initial state, without «remembering» the field.
Their key properties:
High magnetic permeability (µ) — the material virtually absorbs magnetic flux.
Low coercive force (Hc) — minimal resistance during demagnetization.
Low hysteresis losses — efficiency and accuracy even under frequent operating cycles.
These characteristics make such materials indispensable in devices where fast, precise control of magnetic flux matters — from transformers to sensors and navigation systems.
High magnetic properties are achieved not only thanks to chemical composition, but also to heat treatment that forms a special material microstructure — a homogeneous solid solution with minimal internal stresses.
Most soft magnetic alloys are based on nickel (Ni); iron (Fe), molybdenum (Mo), titanium (Ti), and sometimes copper (Cu) or chromium (Cr) are added to it.
Each addition changes the metal’s behavior under an electromagnetic field, making it possible to fine-tune magnetic parameters, mechanical strength, and corrosion resistance.
Composition: about 50% nickel, the rest — iron (Fe).
50Н — a classic alloy for work in constant and low-frequency magnetic fields.
50НП — an alloy variant with a rectangular hysteresis loop.
Structure after annealing: a homogeneous solid solution.
Created in the 20th century in response to instrument makers’ request for high-sensitivity alloys.
Composition: about 79% nickel, 4% molybdenum, the rest — iron.
Features: high magnetic permeability in weak fields, saturation induction 0.65–0.75 T.
Structure: a homogeneous solid solution.
Alloy 79НМ is used in cores of small transformers, relays, and magnetic shields.
81НМА is an alloy where engineering precision is taken to perfection. The letter «А» in the designation means special purity — a minimal content of harmful impurities such as sulfur (S) and phosphorus (P).
Composition: roughly 81% nickel, ~5% molybdenum, ~3% titanium.
Advantages:
high magnetic permeability;
low coercive force — less than 5 A/m;
high mechanical strength — σв = 640–1270 MPa (depending on final heat treatment).
The alloy is not only magnetically sensitive but also mechanically strong — a rare combination for this class of materials. That is why 81НМА became the choice for magnetic heads, flaw detectors, fluxgate sensors, sensors, and high-sensitivity shields.
The magnetic characteristics of nickel alloys depend directly on their heat-treatment technology.
Main stages:
Annealing — removes residual stresses and restores the crystal lattice.
Cooling in a controlled environment — prevents oxidation and ensures stability of magnetic parameters.
After properly performed annealing the structure becomes as homogeneous as possible, which ensures high permeability and minimal hysteresis losses.
Nickel soft magnetic alloys are not merely precision materials, but the foundation of many modern technologies.
50Н is one of the most sought-after representatives of nickel soft magnetic materials. Its main advantage is elevated technical saturation induction and a high capacity for magnetization under an external magnetic field. Thanks to these characteristics the material finds use in electronics where stable energy transfer at minimal losses and compact device sizes is needed.
It is used in producing radio receivers and amplifiers, cores of small transformers, and parts of magnetic circuits operating without bias or with small bias.
In addition, 50Н shows good processability in cold and hot working, making it convenient in series production of magnetic-system elements.
When high stability of magnetic properties at minimal losses is required, engineers choose alloy 79НМ. This material is distinguished by high magnetic permeability, parameter stability over time, and resistance to external effects, making it indispensable when working in weak electromagnetic fields.
The alloy is widely used in producing shields that protect sensitive electronics from external magnetic fields. Thanks to the combination of magnetic sensitivity and process plasticity, 79НМ holds a key place in producing equipment for communication systems, automation, and precision electronics.
This is an alloy for devices where maximum accuracy and minimal losses are required. It has the highest magnetic permeability in both alternating and constant weak fields. It is characterized by reduced sensitivity to vibration and mechanical effects, increased mechanical strength, and characteristic stability even in long-term service.
Various high-precision radio-electronic devices are made from 81НМА. The alloy is especially sought after in measuring equipment, navigation systems, and nondestructive testing devices, where the reliability of the entire instrument depends on the accuracy of the magnetic system.
In the modern world, saturated with electromagnetic fields, protection from interference becomes a critically important task — from medicine to aviation and space.
Soft magnetic nickel alloys provide reliable protection from low- and mid-frequency magnetic fields, acting as an effective «shield» for sensitive electronics.
Advantages of nickel shields:
high shielding effectiveness in the range 10 Hz – 1 MHz;
ability to shield alternating and constant magnetic fields;
possibility of creating multilayer shields (for example, a combination of a nickel layer with aluminum or copper to extend the protection range);
process plasticity — alloys are easily worked and formed.
Where electromagnetic shields are used:
in medical equipment (MRI, EEG, ECG, flaw detectors) — to protect sensitive sensors from external interference;
in aerospace and navigation equipment — to protect gyroscopes, accelerometers, and navigation systems from external magnetic disturbances;
in high-precision measuring electronics and audio equipment — to reduce background noise and signal distortion;
in scientific laboratories and nanotechnology setups — to stabilize the magnetic background during experiments;
in construction — for shielding rooms from electromagnetic fields formed by high-voltage power lines.
The shielding effect is based on redistribution of magnetic flux — a shield made of a material with high magnetic permeability attracts and «closes» electromagnetic field lines inside itself, preventing them from entering the protected space.
Nickel-based soft magnetic alloys are a strategic base of modern electronics and instrumentation and the foundation of technological sovereignty for many advanced industries. The accuracy of medical tomographs, the stability of navigation systems, the energy efficiency of power supplies, and the reliability of control systems depend on their quality.
Thanks to ongoing research and improvement of production technologies at PZPS, alloys of grades 50Н, 50НП, 79НМ, and 81НМА continue to meet the market’s strictest requirements and pave the way to the technologies of the future.
