Hard magnet

C. A. M. van den Broek, Proceedings of the IrdEuropean Conference on Hard Magnetic Materials, Bond Materialen Kennis, Amsterdam, 1973, p. 53. 

G. S. Krijtenburg, Proceedings of the 1 stEuropean Conference on Hard Magnetic Materials, Vienna (unpublished), 1966. 

Table 10. Properties of Permanent (Hard) Magnet Materials ...

Fig. 9. Progress in energy product for hard magnetic materials. To convert to cal, divide by 4.184.

Fig. 10. Demagnetization curves of hard magnetic materials A, Nd2Fe B B, Sm(Co, Cu,Fe,Zr)2 C, SmCo D, bonded SmCo E, Alnico 5 F, Mn—Al—C G, Alnico 8 H, Cr—Co—Fe I, ferrite , bonded ferrite. To convert T to G, multiply by 10". ...

Other RCo single-phase hard magnets in addition to Sm have been prepared both commercially and in the laboratory. These include Sm in combination with Pr, Ce, and Ce-mischmetal (CeMM), this last a very low cost mixture containing about 55% Ce, 25% La, 13% Nd, and 5% Pr. 

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 ... 

EuIn2P2 magnetic susceptibility shows a clear magnetic transition at about 24 K. In Fig. 11.5 c, magnetic susceptibility as a function of the a, a-h, and c direction were obtained on a plate crystal. The a axis exhibits the largest susceptibility and is the easy magnetization direction. The c axis is the hard magnetization direction. 

Texture has a rather marked influence on the properties of a given deposit. Thus, rather seemingly umelated parameters (properties), such as corrosion resistance, hardness, magnetic properties, porosity, contact resistance, and many others, are all texture dependent. By way of illustration, we discuss (6) first the case of magnetic properties. 

A good design for a hard magnetic material is to have small, elongated particles. 

Important is the use of light rare earth elonents for production of hard magnetic materials. Most prominent are alloys of samarium with cobalt in the atomic ratio 1 5 or 2 17. It may also be assumed that in further development of these materials on a larger scale that praseodymium, neodymium, lanthanum and also individual heavy rare ecu h elements will be used to achieve particular effects. Interesting is the development of magnetic bubble memories based on gadolinium-galliiimrgarnets. 

Magnetic materials can be divided into soft and hard magnets, depending on their behavior in the presence of a magnetic field. This is the topic of the next two sections. 

Figure 6.55 Comparison of hysteresis loops for soft and hard magnetic materials. From K. M. Ralls, T. H. Courtney, and J. Wulff, Introduction to Materials Science and Engineering. Copyright 1976 by John Wiley Sons, Inc. This material is used by permission John Wiley Sons, Inc.

Table 6.20 Some Hard Magnetic Alloys and Their Selected Properties...

Coehoom, R., 1990, in Proceedings of the NATO-ASI "Supermagnets, Hard Magnetic Materials , eds... 

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