While there are roughly 10 different alloys, in reality, the North American market supports 2 alloys of magnesium. They are:

AZ31B

and

ZK60A

AZ31B is primarily available in plate while ZK60A is available in round bar, used for machining.

AZ31B comes in cast tooling plate for commercial applications as well as in H24 temper which is most commonly used in defense.

It should be noted..... that magnesium powder is inherently flammable, solid forms are relatively safe to handle. Having said this, we've heard horror stories of entire machine tools being destroyed when light cuts produce powder. Combine this with insufficient coolant and ignition is a great danger.