The Aluminum Nickel Cobalt alloy magnet was developed by General Electric under a war time government contract in 1943. The feds held the patent and made it freely available to all.
Modern "rare earth" magnets are two types. One made with neodymium and the other made with samarium cobalt. they are approximately 55% stronger than Alnico and can be three times as strong as iron magnets. They are very brittle and corrode in any humidity, so they must be plated or sealed in aluminum or plastic to protect them from the elements. . . 😎
