Bismanol

Bismanol, a permanent magnet made from powder metallurgy of manganese bismuthide, was developed by the US Naval Ordnance Laboratory in the early 1950s – at the time of invention it was one of the highest coercive force permanent magnets available, at 3000 oersteds.^[3] Coercive force reached 3650 oersteds and magnetic flux density 4800 by the mid 1950s. The material was generally strong, and stable to shock and vibration, but had a tendency to chip. Slow corrosion of the material occurred under normal conditions.^[4]

The material was used to make permanent magnets for use in small electric motors.^[5]

Bismanol magnets have been replaced by neodymium magnets which are both cheaper and superior in other ways, by samarium-cobalt magnets in more critical applications, and by alnico magnets.^{[citation needed]}