Advanced Alloy

Advanced alloy (not to be confused with IC2 version) is a, well, advanced alloy made from steel and red copper. Despite having an uninventive name, it is very useful in a vast assortment of places. It is used to make tools, armor, superconductors, Advanced Factories, and much more. It has just as much use in electrical components as red copper, maybe more, and they're all mid-late game. Advanced Alloy can be made with the Blast Furnace, or it can be found in Spaceships. When used as an armor or tool material, its capabilities are comparable to that of diamonds in vanilla minecraft.

Practical uses
Other than the obvious use as a superconductor and mid-tier technological component, advanced alloy can be an incredibly powerful tool in the early game. Advanced Alloy Pickaxes can mine through obsidian, and a full set of advanced armor gives the same amount of protection as full diamond armor. Comparatively, it is much easier to obtain, even though it requires more infrastructure to synethsize.

Connections to reality
Steel-copper alloys are used in reality, often for corrosion resistance. The most common example of this is COR-TEN Steel, sometimes known as weathering steel. When the alloy is initially exposed to air and humidity, the outside copper layer oxidizes, providing a protective layer for the steel. Although such alloys do exist, they were not observed to have superconducting properties, and have no strength advantage over normal steel. They also consist of only around 0.25%-0.55% copper, and in most cases, copper is not the main element used in the steel, with the alloy consisting more of manganese, silicon, nickel, or chromium.