I was making some lanthanum chips some days ago by drilling a nugget with an end mill in a drill press. Two days later there is brown rust on the
drill chuck and the vise. Why is this? I know La quickly gets a black coating of La nitride, which according to Wikipedia reacts with moisture to make
ammonia. But I have never heard of ammonia causing corrosion on steel. What gives? I have not had any similar problems when drilling Y or Zr.