1.

Here is Ultrons vibrainium spire that Tony is supercharging for Thors direct hit.

2.

Here is the explosion(by the way the spire took this force directly)

3.

Here is the vibrainium spire 100% intact after the nuke level explosion(the spire definitely took the brunt of that force)

-------

I think this shows that Vibranium is extremly durable to both direct force(Thor hitting it) and it being the epicenter of the explosion shows durability to a massive energy release.