AMS 5666 is a specification for Inconel 625 or Alloy 625.
It is a corrosion and heat resistant Nickel alloy with UNS designation is N06625.
It is typically used for parts primarily requiring corrosion or oxidation resistance at temperatures
up to 2000 deg F.
It is nonmagnetic at room temperature.
Material is in the form of Bars, Forgings, Extrusions, and Rings in the annealed condition.
Room temperature yield strength is 60,000 psi minimum and tensile strength 120,000 minimum
Check the specs!!!

For more info on nickel grade Inconel 625 check the material page here and the long video on alloy 625 here.