Iron magnetic properties

It should be noted that the magnetic properties of iron are dependent on purity of the iron and the nature of any impurities.)... 

Spinel ferrites, isostmctural with the mineral spinel [1302-67-6] MgAl204, combine interesting soft magnetic properties with a relatively high electrical resistivity. The latter permits low eddy current losses in a-c appHcations, and based on this feature spinel ferrites have largely replaced the iron-based core materials in the r-f range. The main representatives are MnZn-ferrites (frequencies up to about 1 MH2) and NiZn-ferrites (frequencies 1 MHz). 

Table 1. Magnetic Properties of Fully Annealed Iron and Iron Alloys ...

Iron—Aluminum and Iron—Aluminum—Silicon Alloys. The influence of aluminum on the physical and magnetic properties of iron is similar to that of silicon, ie, stabilization of the bcc phase, increased resistivity, decreased ductility, and decreased saturation magnetization, magnetocrystalline anisotropy, and magnetostriction. Whereas Si—Ee alloys are well estabHshed for electrical appHcations, the aluminum—iron alloys have not been studied commercially. However, small (up to ca 0.3%) amounts of A1 have been added to the nonoriented grades of siHcon steel, because the decrease in ductiHty is less with A1 than with Si. 

Chromium—Cobalt—Iron Alloys. In 1971, a family of ductile Cr—Co—Fe permanent-magnet alloys was developed (79). The Cr—Co—Fe alloys are analogous to the Alnicos in metallurgical stmcture and in permanent magnetic properties, but are cold formable at room temperature. Equivalent magnetic properties also can be attained with substantially less Co, thereby offering savings in materials cost. 

Vanadium—Cobalt-Iron Alloys. V—Co—Fe permanent-magnet alloys also are ductile. A common commercial ahoy, Vicahoy I, has a nominal composition 10 wt % V, 52 wt % Co, and 38 wt % Fe (Table 10). Hard magnetic properties are developed by quenching from 1200°C for conversion to bcc a-phase foUowed by aging at 600°C (precipitation of fee y-phase). The resulting properties are isotropic, with ca kJ/m ... 

With respect to magnetic properties, the intrinsic magnetic susceptibiHty of pure chrysotile is very weak. However, the presence of associated minerals such as magnetite, as weU as substitution ions (Fe, Mn), increases the magnetic susceptibiHty to values around 6 x 10 m /kg. With amphiboles, the magnetic susceptibiHty is much higher, mainly because of the high iron content typically, amosite and crocidoHte exhibit susceptibiHty values of 100 and 75 X 10 m /kg, respectively (23). 

Another material that has permanent magnetic properties is neodymium—iron—boron, Nd2Fe24B. For an in-depth discussion see reference 7. 

Magnetic properties of iron nanocrystals nested in carbon cages, which grew on the cathode deposit, have been studied by Fliura el al.[29]. Magnetization (M-H) curves showed that the coercive force. He, of... 

The pressure sensitivity of the magnetic properties of the Invar alloys is indicated by extensive measurements of the coefficient of saturation magnetization change with pressure M dMJdP for various compositions as shown in Fig. 5.10. The exceedingly large values in the 30%-40% Ni range are evident and much in excess of the values for iron and nickel. The 30-wt% Ni composition in the fee phase is the most sensitive to pressure, whereas this... 

See p. 500 of ref. 24 for a description of Ihe garnet structure which is also adopted by inany. synthetic and non-silicaie coniponnds these have been much stndied recently becan.se of their important optical and magnetic properties, e.g. ferrimagnetic vitriuni iron garnet (YIG), y> Fe (Al" b4),. 

M. W. Grinstafif, M. B. Salmon, and K.S. Suslick, Magnetic properties of amorphous iron,... 

In addition to nickel alloys, nickel also forms an important alloying element in stainless steels and in cast irons, in both of which it confers additional corrosion resistance and improved mechanical and engineering properties, and in Fe-Ni alloys for obtaining controlled physical and magnetic properties (see Chapter 3). With non-ferrous metals nickel also forms important types of alloys, especially with copper, i.e. cupro-nickels and nickel silvers these are dealt with in Section 4.2. 

The specific heats of solids at low temperatures are appreciably less than at higher temperatures. A maximum specific heat has been observed in the case of iron at 740° and nickel at 320° (Lecher, 1908). Since these are the temperatures at which recalescence and loss of magnetic properties occur, the close relation of specific heat to molecular structure is evident. 

We have already mentioned some of the important roles that the d-block metals play in virtually every aspect of our lives. Steel, an alloy based on iron, is important in construction and transportation and the nonferrous alloys, those based on other metals—most notably, copper—are also important in industry, for their corrosion resistance and strength. Some of these alloys are also desired for their magnetic properties. 

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