| 420 / | HD | ALLOYS OR METALLIC COMPOSITIONS |
| 441 | DF | NICKEL BASE {6} |
| 442 | DF | .~ Chromium containing {5} |
| 445 | DF | .~.~ Aluminum containing {1} |
| 446 | | .~.~.~ Titanium containing {3} |
| 447 | DF | .~.~.~.~> Tantalum, niobium, vanadium, or hafnium containing {1} |
| 449 | DF | .~.~.~.~> Zirconium or boron containing |
| 450 | DF | .~.~.~.~> Molybdenum or tungsten containing |