Hard magnetic alloys

All of the hard magnetic materials are based on choosing a base alloy with a sufficiently high saturation magnetization Mg and a high magnetocrystalline anisotropy constant K, and tailoring the microstructure to exploit this crystal anisotropy. In some cases, shape 

Magnets are manufactured eitha- by a casti ng/hcat treatment technique or by a powder metallurgical process. Powder metallurgy is 

C magnets produced by cast and heat treatment P magnets produced by means of powder metallurgical techniques 

In some of the hard magnetic materials two of these variants of microstructural design are combined. 

Alloy components (wt%) Mode of manufacturing and heat treatment Magnetic prop Cities  

Magnetic materials based on the Fe—Co—V alloy system were the first ductile magnets. The intrinsic magnetic properties may be found in [3.6] while extensive magnetic materials data are treated in [3.56]. The optimum magnetic behavior is obtained for alloy compositions around Fe-55 wt%Co-10 wt% V. As the isothermal sections of the Fe—Co—V phase diagram Fig.4.3-56a and Fig.4.3-56b show, this alloy is mainly in the fee y-phase (austenite) state at 900 C, 

Composition nominal wt% Variant Remanence (T) Coercivity (kAm-i) Enei y density (kJm- ) Curie temp- erature (°C) Maximum application temperature (°C) Hardness HV Commercial designation  

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

Explain in terms of your answer to Problem 3 why many of the hard magnetic alloys are based on cobalt. 

Fruchart D., Miraglia S. (1991) Hydrogenated hard magnetic alloys from fundamental to applications (invited). J. Appl. Phys. 69(8), 5578-5583. 

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