Grade of alu for axe?

[Graw]

I was considering interchangable heads, so I could have the bludgeoning hammer made up from alu and a more THZ shaped axe head made up from hardox (I could use a nice thick piece of hardox since the alu head will weigh around 1.5kg I'll have that much weight to play with). It would be decent that I could change them around as per which is more suitable for who im up against.

You're right about the alu looking cooler, I've seen killer joule and tbh its one of my main inspirations behind my build - such a cool machine. Does the pick axe shape end up getting stuck in armour alot? Going through 10mm of HDPE is pretty impressive, got any pics of the robot?

Edit : http://www.ebay.co.uk/itm/10mm-RAEX-...5a1e-NLMfLDPNA

Good grade for what I need?