Available and new permanent magnet materials

Five major classes of permanent magnet materials are available for engineered devices. The magnetic and other physical properties of appropriate subgrades are listed for applications. Hard ferrite and samarium-cobalt magnets are compared to the newest and, in some ways, the best material in production today—the neodymium/iron/boron. The magnetic and physical properties, availability and relative costs of appropriate subgrades are presented. High coercivity SM2TM17 performs better at elevated temperature than SmCo5 or Nd-Fe-B—performance is generally improved by designing with higher operating slope in the magnet application.