I think levels of impurities and surface treatment of the metal may cause variation in whether something is considered suitable or not? For example, from [0] (

I think levels of impurities and surface treatment of the metal may cause variation in whether something is considered suitable or not? For example, from [0] (which is declassified from 1974!) : "Titanium can react violently with strong oxidizers if the oxi-dizer penetrates the oxidized surface layer." "Free chloride, ions in nitrogen tetroxide can cause an accelera-tion of intergranular corrosion in titanium."