iPhone 5 to have aluminum back, new antenna design?

Hopefully this comes to fuition.  An aluminum back would provide more protection however, I could foresee us going back to the complaints of phones getting scratched.  Here's an idea, how about making the phone out of a lightened version of tungsten carbide.  I have a ring made out of this stuff and it is nearly bullet-proof. No scratches and super durable.  

9to5mac