Whether an asteroid survives the fall through the atmosphere depends on its size and structural integrity. Our understanding of large impacts is limited (we haven't observed any, and this is a very good thing) Howver there is a calculator that can use current knowledge to forecast what would happen.
For a one mile iron asteroid, hitting the atmosphere at 17km/s at an angle of 45 degrees, it would pass through the atmosphere and hit the ground relatively intact. If it hit sedimentary rock, it would carve out an initial crater that is is 7.5km deep and 21 km wide, though this would collapse and fill to give a final crater 800m deep and 35km wide.
At 100km from the impact, many buildings would be destroyed by violent shaking, and any trees would burst into flame from the heat of the fireball, which would be 300 times brighter than the sun.
Five minutes after the impact, a blast of wind at 1000mph would hit and flatten everything else.
In case it's not obvious, although the asteroid would survive the passage through the atmosphere, it wouldn't survive the impact. Some of the asteroid would merge with the melted rock in the crater, other parts of it would form part of the ejecta that would fall around the crater.
Smaller asteroids are likely to break up (explosively) in the atmosphere, however the chunks then slow down and hit the ground at hundreds of mph, and not at hypervelocity. These chunks would then be meteorites, and iron meteorites are known.