All All Grades of Nitinol the Same?

Are all grades of Nitinol the same in terms of their UTS or are some stronger than others? I understand that nitinol wire has a UTS of about 1GPa but I am wondering if there are differences between suppliers and/or alloys? Are they all 50:50 Ni:Ti or do trace elements make a difference?

For my application I want a wire that has the super elastic properties of Nitinol but is also strong. The wire moves from a delivery state to an expanded state so it needs to resist high strians without plastic deformation. It is an advantage if I can make the wire stronger without having to increase the diameter.

Thanks,

EamonB