Q: Can I use Molybdenum outside of a vacuum?
A: Yes and no. It can be used outside a vacuum but it is much more limited, especially if in an oxygen rich environment. The catch is if you use Molybdenum outside a vacuum (in an oxygenated environment) the temperature MUST be less than 600F or molybdenum screws will quickly oxidize. In a vacuum, molybdenum fasteners can be used at my higher temperature – up to ~2900F but also could be used at they high temperature in an inert gas environment.