Nickel base alloy

A gamma prime strengthened nickel base alloy having a 1650 DEG F impact strength of at least 6 ft.-lbs. after 35,000 hours exposure at 1600 DEG F. The alloy consists essentially of, by weight, from 12.0 to 20.0% chromium, from 4.75 to 7.0% titanium, from 1.3 to 3.0% aluminum, from 13.0 to 19.0% cobalt, from 2.0 to 3.5% molybdenum, from 0.5 to 2.5% tungsten, from 0.005 to 0.03% boron, from 0.005 to 0.045% carbon, up to 0.75% manganese, up to 0.08% zirconium, up to 0.5% iron, up to 0.2% of rare earth elements that will not lower the incipient melting temperature below the solvus temperature of the gamma prime present in the alloy, up to 0.02% of elements from the group consisting of magnesium, calcium, strontium and barium, balance essentially nickel.