Neodymium-iron-boron magnet thermal failure in electric vehicles

Tom's two Chevy Bolts use Dy-Fe magnets (180°F tolerance) rather than Nd-Fe-B (140°F). Military interest for nuclear-reactor-powered ships.

I have two all-electric vehicles, Chevy Bolts. They don't use neodymium iron in the electric motors in my car. Anybody know what they use? Dysprosium iron. Why? Because neodymium iron starts to lose its great magnetic properties at 140 degrees Fahrenheit. Dysprosium iron will go to 180. When someone's gunning that car they're liable to get it hot, particularly if you're in Arizona, and then all of a sudden you lose your power if you go above the transformation. Who else is interested in dysprosium iron? The US military. They have a number of applications such as nuclear reactors powering ships that would like that extra forty degrees of safety margin. So there's all kinds of things that follow on from these different things.

Even if you're interested in something like dysprosium — why should you be interested in dysprosium? Mischmetals are good for sparks because if you do mechanical friction you get a very rapid spark; they like to burn in air. But dysprosium in particular — anybody heard of neodymium-iron-boron magnets? The problem with neodymium-iron-boron magnets is they're very strong, but their Curie temperature is like 140 degrees Fahrenheit. For example, I bought two all-electric vehicles in June. Now I'm gas-free — not completely; my wife has one of the two and I have the other, but we have a third car that's gas in case we want to go on a long trip, because these things only have a 200 to 240 mile range. They have dysprosium magnets in the motor, because dysprosium-iron-boron will go to 180 or 190 degrees Fahrenheit. Some of these motors, if you push them real hard in the mountains, can get above 140, and all of a sudden your motor won't work. So dysprosium-iron-boron is sort of replacing the neodymium [neodymium-iron-boron] where you need higher temperature. If someone was interested in dysprosium as an element, you could write a whole 10-page paper on it. You could actually write a whole book on most of these things.