Magnetic permeability. For the characteristic of behavior of magnetic materials in the field with intensity of N use concepts of absolute magnetic permeability of a and relative magnetic permeability of 0:
Among alloys on the basis of rare-earth the greatest value intermetallic connections of the RCo5 type, where have R – rare-earth metal. In connection brand the letter K means cobalt, With – samarium, P – praseodymium.
Other magnetosolid materials. Materials which have highly specialized application belong to this group: plastically deformable alloys, elastic magnets, materials for magnetic data carriers, liquid magnets.
Alloys on the basis of rare-earth metals are received cold pressing of powder of an alloy of RCo5 to high degree of density, agglomeration of briquettes from powders in the presence of a liquid phase and molding of multicomponent alloys in which cobalt is replaced with copper and iron.
Cast materials on the basis of alloys. These materials have a basis alloys iron-nickel - aluminum (Fe-Ni-Al) and iron-nickel - cobalt (Fe-Ni-Co) and are the main materials for production of permanent magnets. These alloys carry to precision as their quantity to a great extent is defined by strict observance of technology factors.
Losses on a hysteresis are created in the course of shift of walls of domains at an initial stage of magnetization. Owing to heterogeneity of structure of magnetic material magnetic energy is spent for movement of walls of domains.
effect of irreversible loss of magnetic properties after cooling of a magnet up to the temperature - 60C and below (after cooling and the subsequent heating to reference temperature magnetic properties are not restored).
Powder magnetosolid materials (permanent magnets). Powder magnetosolid materials apply to production of tiny permanent magnets of a difficult form. They are subdivided on ceramic-metal, metalplastic, oxidic and micropowder.
Plastically deformable magnets possess good plastic properties; well give in to all types of machining (are well stamped, scissored, processed on metal-cutting machines); have high cost.
Continuous metal tapes and wire from are used generally in the special purposes and during the work in the wide range of temperatures. The wire from stainless steel 0,1 microns thick possesses the coercive force of Ns=32 of kA/m, residual induction of Br = 0,7T and effort of a gap 15H.
Magnetosolid materials are of great importance of coercive force of Nanosecond, are difficult magnetized, but are capable to keep a long time magnetization. They possess a wide loop of a hysteresis with a big coercive force of Nanosecond> 4 kA/m (rice 3, and existence of the one-domain structures arising in small volumes of magnetic substance.
Materials for magnetic data carriers represent metal tapes and a wire from magnetosolid materials, continuous metal, bimetallic and plastic tapes and magnetic powders which are applied on tapes, metal disks and drums, magnetic rubber, etc.
As a result receive the system consisting of not magnetic phase 2 with one-domain silnomagnitny inclusions of the phase which possesses by the big coercive force of Nanosecond. Such alloys do not apply because of rather low magnetic properties. The greatest alloys iron-nickel – aluminum, alloyed by Cu copper and cobalt With are widespread.
The main curve of magnetization (rice has a number of characteristic sites which can be allocated conditionally at magnetization of a monocrystal of a ferromagnetic. The first site of a curve of magnetization corresponds to process of shift of borders of the less favorably focused domains. On the second site there is a turn of vectors of magnetization of domains in the direction of an external magnetic field. The third site corresponds to paraprocess, i.e. the final stage of process of magnetization when the strong magnetic field turns not oriented magnetic moments of domains of a ferromagnetic in the direction of the action.
Receive ceramic-metal magnets as a result of pressing of metal powders without binding material and their agglomeration at high temperatures. For powders use YuNDK alloys (the Fe-Ni-Al-system alloy alloyed by cobalt); on the basis of platinum (Pt-Co, Pt-Fe); on the basis of rare-earth metals.