Hi folks,

sorry,...but I think your'e all wrong .....
for my opinion there's only one reason for the use of aluminium for the coils.........

It's the reason of the isolation between the windings.
When you use aluminium theres the posibility to use the electricaly produced (its very easy) ISOLATION as Al-Oxid coating.
This very thin coat is very highly temperature resistant too.
With Cu coils you have to use a laquer coating which is only resistant to about 280 C°. (You can smell it when overheated)
The used aluminium does additionaly have a very low temperature depending movement and variation of the lenght.

with a little hope to help...

HP