In many sci-fi scenarii, most often when mechs are involved, it is not uncommon to see such a technology, usually called heated blade. Supposedly, it would make the blade even more efficient at cutting through anything; usually designed to cut through or pierce metal plating, melting it in the process.
Now the thing is, I love this kind of idea (if only for its sheer awesomeness, just like vibrating blades), but there is no way for it to work the same in real life; the temperature would need to be absurdly high to melt any metal that fast. Besides, the blade needs to have a higher fusion point, and with a temperature that high, I doubt there is anything that would work.
But I started wondering: given we are sufficiently technology advanced (assume at least common space travel, maybe even FTL-level if needed), how close can we get to it? As of today, the closest we have that I can think of are what is essentially a blade-shaped soldering iron, but that's because we have no need for heated weapons.
What if we can put it Up To The Next Level?
Restrictions and notes:
- The blade has to be solid; otherwise I could easily imagine lightsabers or futuristic blowtorches to be the ideal solution.
- It has to significantly increase the blade's cutting power. Glowing knives are cool but I want something that can do more than slice and toast bread at the same time.
- Any alloy or technology is allowed, as long as it's scientifically explainable. Does your sword uses the power of a nuclear plant in order to work? Alright no problem, as long as you can explain how to miniaturize all that in the blade (although I accept external solutions like powered suits).
- Of course we can handwave that, if such a material that can withstand such a temperature while maintaining a decent hardness is found, it is not often used for armor plating; maybe because of the cost.
- Size does not matter; if the blade has to be 10 feet long to accommodate for the needed technology, and as such can only be used by a mech, that's fine. All the better if you can make it human-sized, however.
Of course, I'm interested in the How, not in the Why. Never in the Why.