Magnesium automobile wheels corrosion in road salt

"Mag wheels" pitting within a year despite clear coat — used to teach magnesium's extreme position on the galvanic series. Notes that modern "mag wheels" are actually aluminum.

Yeah, a NASCAR vehicle is worth how much, about a half a million to a million dollars, right? You can afford it, and you only have to drive it for 500 miles. Sort of like a cruise missile — it has to last for an hour and a half, the engine in a cruise missile, limited time life. So NASCAR. But there are actually a lot of people driving around on magnesium wheels — mag wheels — on a car. Turns out most mag wheels today are actually aluminum. In the old days they were magnesium, and they would start pitting after a year. They'd put clear coat on them and all this other stuff, and they would still start pitting when they're made out of magnesium. So they mostly make them out of aluminum, but they'd love to make them out of magnesium, and they did make them out of magnesium.

Why automotive magnesium retreated under the dashboard. Road salt → magnesium chloride solubility.

Magnesium has several Achilles heels. The U.S. Department of Energy has been spending probably a hundred million dollars a year since their inception forty or fifty years ago, because they're going to put magnesium in automobiles. Steel is too heavy, aluminum is lighter, but magnesium is even better. They started putting more magnesium in cars — there might be twenty pounds of magnesium in an average automobile today. Where does it go? It used to be more — they used to make mag wheels of real magnesium. Now what they call mag wheels are usually made out of aluminum.