Room- and elevated-temperature fatigue crack growth in damage tolerant niobium aluminide intermetallics

The effects of temperature on the fatigue crack growth behavior of damage tolerant niobium aluminide intermetallics (Nb-15Al-40Ti and Nb-12.5Al-41Ti-1.5Mo) are discussed in this paper (compositions quoted in atomic % unless stated others). Room-temperature fatigue crack growth rates in this alloy are shown to be comparable to those in pure Nb and mill annealed Ti-6Al-4V. However, the fatigue crack growth rates in laboratory air at 750 degrees C are slower than the room-temperature fatigue crack growth rates in the near-threshold regime. The slower elevated-temperature crack growth rates are attributed to the combined effects of oxide-induced crack closure and crack-tip blunting.