We know for sure that MJOLNIR is composed of a Titanium alloy. We do not know what elements are included in this alloy (besides Titanium), so we can only make an educated guess.
What elements do you believe are involved in the Titanium alloy used to make MJOLNIR armor, and why?
This question applies to Mark IV, V, and VI. It only involves the elements existing today, and does not include the possibility of any possible undiscovered future elements.