This is a weapon design for the direaxe (or double axe) known as Skyforge, Leeto's personal weapon.
I wanted to play around with some ideas for an axe which evolved into a direaxe design, as well as to steer away from the 'traditional' axe design, so I came up with the circular blade design.
This is the 'fourth' evolution for the weapon, so there are others before this, influenced by Dynasty Warriors and Samurai Warriors.
Photoshop CS3.
Skyforge axe design and art are mine.
There isn't a special name for the alloy, it's just some information and flavor to add to the weapon's history and description.