You don't
have to stick with just alloys, you know. Some ideas I've been playing around for armor:
(Carbon) Buckypaper: Carbon nanotubes, each with extremely high tensile strengths, "weaved" together like a cloth or paper. Makes a low-weight, high-tensile material incomparable to anything else known (not including fictional materials, of course). This high tensile strength could make it effective at flat out nullifying projectile weapons and concussions from explosive weapons. It has a high thermal and electrical conductivity which could make it vulnerable to energy weapons -- Or excellent at absorbing them, if you add some sort of heat sinks.
sp3 Buckypaper: Similar principles as the above. By trading out the sp2 (nanotubes) bond for a sp3 (diamond) bond, you reduce tensile-strength-per-nanotube somewhat, but allows you to create a much more densely-packed armor weave.
Energized Tungsten: (
https://stararmy.com/forums/viewtopic.php?p=41065 ) I used Tungsten because it is one of the toughest substances on the elemental table (against both kinetic and energy weapons), and I didn't want to try mucking about with the physics of using some made-up alloy. But the energized armor system should be able to work in conjunction with most metal to increase a pounding a ship can take.
This would be an extreme effective second line defense for ships with shielding; when the shield emitters break, your primary reactor will still be pumping out huge amounts of energy. Just divert all the power into your Energized Armor capacitor to increase its defensive potential exponentially.
"Plan B": An idea of mine for damage control, rather than damage prevention. Have all hulls and bulkheads lined with a gel substance. When the hull is breached, atmosphere (probably oxygen) will leak through the breach, thereby contacting the in-between gel layer. The gel would react with the oxygen, cause it to rapidly expand and eventually harden, turning a breached room into a temporary block of armor. Or plugging up a hole in the hull. Not really a construction material, but an interesting idea nonetheless.
Electroactive Polymers: The basis for artifical muscles used by Freespacer machines; Metals whose shap is modified when voltage is applied. Theoretically this could have a military application, by having an armor that "hardens" (contracts) when you pump power into it.