Is any metal as strong as vibranium

Here's an older handbooks info on Adamantium, that also helps explain Captain America's shield.
Both are alloys, not pure metals. The addition of vibranium enhanced the properties of the Iron alloy, which might explain why Capt America's shield absorbs some portion of an impact (as evidenced by him taking a blow from the Hulk) without being catapulted miles away.

"Adamantium is a virtually indestructible man-made steel alloy which does not occur in nature and whose exact chemical composition is a government classified secret. Adamantium is not an element: its properties do not qualify it for any know space on the Periodic Table of Elements. Rather, Adamantium is a series of closely related compounds of iron created through a secret process discovered by the American metallurgist Dr. Myron MacLain.

MacLain began experimenting with the process that created Adamantium as a young scientist in the employ of the government in the early 1940s. Assigned to create a super-metal with which to build tanks, MacLain labored for month, experimenting with various iron alloys. One of his experiments utilized the rare meteoric ore now known as Wakandan Vibranium. He tried to fuse the Vibranium to the iron alloy numerous times without success. Then one night when he dozed off, some as yet unknown factor entered the process, and permitted the fusion to occur. Upon discovering his success, MacLain poured the molten metal into a disc-shaped mold. The disc, once solidified, has proven to be the most impervious object ever created on Earth. MacLain turned the discover to the government and it was given to Captain America to use as his shield. Neither MacLain nor anyone else has ever been able to discover what was the x-factor that entered the process, or has been able to fuse Vibranium with another metal. (The unknown iron-Vibranium alloy of which the shield is composed resembles True Adamantium, although Adamantium itself contains no Vibranium,)

Over the following decades MacLain experimented, attempting to duplicate the process that create the shield. Finally, in recent years, he succeeded in developing the process by which the substance known as True Adamantium is created. True Adamantium is nearly as strong as Captain 's shield, and is, for all practical purpose, indestructible. The degree of impermeability varies directly with the thickness of the Adamantium. A direct blow from Thor's hammer, conveyed with the thunder god's full strength, will slightly dent a solid cylinder of True Adamantium. A sufficient mass of Adamantium could survive a direct hit from a nuclear weapon.