I'm not really sure where to post this question:
As a trombone player, I've never understood why aluminum is never used in brass instrument manufacturing. It's seldom mentioned on the internet either. Mutes and such are often made with aluminum and there's no problem with workability there. Even small things like cross-braces are never aluminum.
And I don't think is a cost issue (if anything, isn't aluminum cheaper than brass?). Sterling silver is used on a lot of trombones bells ("king silvertone"), so it can't be a cost issue.
Is it a durability issue? Aluminum can be very resistant to distortion (bike frames). In my experience, aluminum mutes (one of those cup/straight jo-rals) are extremely well built, so durability doesn't seem like an issue.
My guess is that it's a sound issue. Would an aluminum instrument sound too shrill? I always thought at the end of the day, material still makes less of an impact to the sound than shape does.
Am I just missing something really obvious??