Neutrino,

I'm guessing slightly on the metallurgy here but I don't think the hard drive (IDC) connector crimp pins are made from aluminium at all, they are made from gold or tin (cheap) plated low/medium-carbon steel and not aluminium? Aluminium would not have the required hardness to pierce the PVC cable sheath and bite into the inner conductor(s) during assembly?

I wholly agree with you on the co-efficient of linear expansion thing btw but I really don't think it's applicable here. I guess this could be proved with a magnet, if i can find a suitable one in the next few mins I'll come back and edit this post.

Rue