The Japaneese discovered in 1931 that Aluminum alloyed with Iron improved its magnetic properties. In 1942 after the outbreak of hostilities with the Axes powers, General Electric was given a government contract to improve the mix. They came up with an alloy in 1944 of aluminum. cobalt, nickel, copper, Iron and other trace elements that was a very strong magnet in one direction. Not so much when the poles were reversed.. This is why you must pay attention when recharging them. This is the formula used in modern magnetos. Amazingly they retain their shape and magnetism when red hot, ( over 1000 degrees F,) enabling them to be used in cast aluminum. Evinrude was experimenting with them in 1945 and came up with the new magnetos that were on the under 10 horse models in 1947,, after the supply of old magnetos was exhausted.
