As far as I'm aware, Vibranium was exclusively in Wakanda (except for the Vibranium that Ulysses Klaue stole and later gave to Ultron and the Vibranium from Howard Stark that is in Cap's Shield). So how is it possible that Tony Stark has Vibranium?
According to the novelization of Iron Man 2, the new element that Howard Stark synthesized which Tony used to replace the Palladium in the arc reactor is vibranium, although this is not referenced in the film. I don't have a direct quote, but this site summarizes it as:
Cut back to Stark who is building something with lasers and a centrifuge. Jarvis analyzes the molecule. Unknown element, similar to Vibernum, Uranium and Ourains. Jarvis projects an image of endless interlocking triangles forming a circle. He dubs it Vibranium. Stark creates some and pour it into a mold.
From the MCU wiki notes on vibranium, the glowing material seen in Iron Man 2 does resemble their concept of raw vibranium.
Black Panther production designer Hannah Beachler says "we've come up with this sort of blue, kind of glowing rock. We went around a lot about like, what is vibranium, because we see it in Cap's shield and it’s very much a metal, so we have different stages of vibranium. We’re going to see it a lot in its raw form, not the alloyed form which is sort of the stainless look." source
The process for synthesizing the new element does seem to require a great deal of power, so it might not be efficient to synthesize more than the small amounts necessary for the reactors, and for the claws in the Mark 33.