High Br, relatively high Hc, high BHmax, lower in cost than Samarium Cobalt, temperature sensitive, and susceptible to oxidation. With careful design, some grades will function up to a maximum of 210 C. Energy product ranges from 1.0 MGOe to about 48 MGOe. Samarium Cobalt A class of Rare Earth material, available in both sintered and bonded forms. Most grades function well up to about 350 C. Energy product ranges from 18 MGOe to about 32 MGOe. Alnico An alloy of aluminum, nickel, and cobalt, Alnico magnets have been popular since the 1930s.
Alnico magnets are available in cast and sintered forms.
Extensively used in rotating machinery, Alnico magnets exhibit high Br, but low Hc, and BHmax in the 5 MGOe range. They are relatively easily demagnetized, resisting oxidation well. Energy product ranges from 1.4 MGOe to about 7.5 MGOe. Composed of Barium or Strontium Ferrite, these materials exhibit good resistance to demagnetization, and are the lowest cost materials available today. Sintered Ferrite magnets are hard and brittle and are extensively used in consumer products.