I have brought this up some time ago in discord (searchable under "aluminium brass". Apparently "brass" is only for copper+zinc though.), but I just remembered this for some reason and thought I'd turn it into an issue so the thought doesn't get lost.

Basically I suggest introducing aluminium bronze as a new alloy of copper and aluminium. Cosmetics aside (fancy new sheet metal blocks), having bronze replace copper in recipes where the copper would be present for vaguely mechanical purposes (mechanical components, or casings (grips/block casings/catridge casings/...) would make it a bit more "realistic" and the color of the metal used would fit the block/item textures more.
More importantly, it would:
a) give a bit more regular gameplay use to aluminium ore/bauxite (so far in the non-cosmetic world it's only required for HV lines and the toolbox) and
b) would make the alloy kiln a required stepping stone, because you can't just rush to the crusher for dust mixing anymore, since it would require aluminum bronze for the engineering blocks, giving it more justification. Also giving it more reason to exist by introducing a second a third alloy :)

A counter argument would be additional clutter, but i think that's negible because no additional ore is added and the bronze just falls in line with the other cosmetic metal blocks. Maybe the copper sheet metal can be green now, too, and the bronze can be the shiny orange blocks :)

Also this might necessitate adjusting ore spawnrates of bauxite and copper ore, but chances are it's just gonna be fine as is.

I've already said I have no plans to add this =P

you can add custom alloys yourself by means of other mods, and use the kiln for that. Funny, I was thinking about doing aluminum bronze as well :p