Hardness vs Brittleness Aluminum

[snowJT]

I'm wondering if anyone is willing to share some comparison numbers between any aluminum's hardness value and its impact resistance value.

A friend and I are disagreeing on something, I think the harder the treatment is, the more brittle it becomes. He doesn't think so.

 

[mpm]

I don't have any kind of numbers, facts or figures on me, but I am a material engineer. Generally, whenever a material is hardened, it becomes more brittle in a sense. It doesn't mean that it becomes brittle, but the material loses its ductility. That is the reason for say annealing. It keeps the hardness levels, but it returns the materials ductility.

Hope that helps a little.