Do all missile modules use Titanium-70 in Endless Space?

Solution 1:

AFAIK only Ion Torpedoes make use of the production bonus. Maybe in the future (or in some expansion or DLC) they add further modules, but anyhow Ion Torpedoes are really good in the early game to establish a significant firepower difference. Later on (early to mid game), as your production capabilities get better, the production bonus gets less and less significant compared to the loss of firepower you get from using them.

Solution 2:

Only Ion Torpedoes require Titanium-70. If you don't have any Titanium-70 early on, you can push through the military tree to reach the second tier missiles, Unstable Torpedoes.