Soft magnetic alloys play an important role in modern industry. Their unique magnetic properties are sought after in electronics, electrical equipment, and other high-tech industries. In this article we look at the main parameters, physical principles of operation, and characteristics of materials produced by the PZPS plant.
Main parameters and concepts
Magnetization (I) reflects the degree of magnetic state of a material and is measured as magnetic moment per unit volume. This vector quantity is directed along the lines of the external magnetic field and is closely related to field strength.
- Magnetic moment characterizes the intensity and direction of magnetic action, determining a material’s ability to create or change a magnetic field.
- Magnetic field strength (H) shows with what force an external field acts on moving charges or magnetized bodies.
- Magnetic induction (B) reflects how strongly a material is magnetized under an external field.
These parameters form the basis for analyzing magnetic properties of various materials. The difference between ferromagnetics, diamagnetics, and paramagnetics is largely determined by the values of these characteristics.
The magnetization vector (J) describes how strongly a material can respond to an external magnetic field. For different material types this response can differ significantly:
- in ferromagnetics, magnetization persists even after the external field is removed;
- paramagnetics have weak positive magnetization that disappears when the field is removed;
- diamagnetics have negative magnetization directed against the external field.
The magnetization vector is used in electromagnetism to describe interaction of a magnetic field with materials, including analyzing magnetic properties of steels and alloys (for example in electronics and instrumentation), calculating magnetic circuits and magnetic shields, and describing processes related to hysteresis and magnetic saturation.
Magnetic induction and material properties
Magnetic induction determines the force and direction of a magnetic field’s effect on a material. Its magnitude depends on the substance’s properties:
- Ferromagnetic materials such as iron, nickel, cobalt, and numerous alloys of these metals have high magnetic induction due to significant magnetic permeability. After the external magnetic field is removed they retain a significant part of magnetization (residual magnetic induction). To demagnetize a ferromagnetic, a certain reverse field called coercive force must be applied.
- Paramagnetics — many iron salts, rare-earth elements, metals of the platinum and palladium groups, sodium, potassium, oxygen, and ferromagnetics above the Curie point. They have weak positive magnetization that does not cause noticeable hysteresis — lag of magnetic induction change relative to change in external magnetic field strength. Their permeability does not depend on the external field and either does not depend on temperature at all or decreases with rising temperature.
- Diamagnetic materials show magnetization directed opposite to the external field, with permeability below unity. Entering a magnetic field, they are repelled toward a region of weaker field. Many metals and most non-metals are diamagnetics. Unlike paramagnetic and ferromagnetic materials, diamagnetic properties practically do not depend on temperature.
These differences determine application areas of materials, from precise measuring instruments to powerful electromagnets.
Magnetization characteristics
The process of magnetizing materials in an external field is described by key characteristics:
- Magnetization curve — a graph showing how a material responds to change in magnetic field strength. If an unmagnetized iron specimen is placed near a magnet or introduced into the magnetic field of an electric current, it becomes magnetized. Magnetization of a material in an external field is described by a curve representing magnetization I or induction B in the specimen as a function of external field strength H. These curves are of fundamental importance in describing magnetic properties of materials.
- Hysteresis loop — reflects residual magnetization (at H=0) — a material’s ability to retain magnetization after the external field is removed, and coercive force (at B=0) — the field strength at which magnetic induction becomes zero during demagnetization. It characterizes a material’s ability to retain a magnetic state.
These parameters are important when choosing material for devices that require high resistance to demagnetization or stable retention of a magnetic state.
Magnetic permeability
Magnetic permeability shows how effectively a material amplifies a magnetic field.
- Initial permeability (as B and H tend to zero) is measured under weak external fields and reflects material behavior at the initial stage of magnetization.
- Maximum permeability is reached under optimal conditions and demonstrates the peak of material efficiency.
These parameters determine application areas of soft magnetic materials, from transformers to measuring devices.
Magnetostriction
Magnetostriction is a change in material dimensions under a magnetic field.
- Linear magnetostriction is expressed as change in specimen length along the field.
- Volume magnetostriction characterizes overall volume change. For most materials the relative volume change of a body on magnetization is significantly smaller than the relative length change.
The magnetostriction effect is important for designing devices where a magnetic field affects mechanical deformation, for example in ultrasonic transducers or actuators.
Soft magnetic alloys of the PZPS plant
The PZPS plant produces electrical steels of grades 20895, 20880, 20860, 20832, 21895, 21880, 21860, 21832, and also offers a wide range of soft magnetic materials with unique characteristics:
- 50N — high magnetic permeability, suitable for transformers and electromagnets;
- 50NP — an alloy with a rectangular hysteresis loop, used in pulse technology;
- 79NM — high permeability in weak fields, used in precision instruments;
- 80NM — easily saturates under weak fields, sought after in radio electronics;
- 81NMA — the best choice for weak fields thanks to maximum magnetic permeability;
- 27KKh — a material with a high Curie point (950°C), suitable for high-temperature applications;
- 49K2FA-VI — magnetic saturation up to 2.35 T and high magnetostriction, ideal for powerful generators.
Our steels and alloys provide stable characteristics and meet the strictest requirements of modern industry. Contact us to discuss your needs and find the optimal solution for your project. PZPS is guaranteed success for your developments!
