Published online by Cambridge University Press: 01 January 1992
Near Nb3AI alloys, having Nb3Al with the ordered A15 crystalographic structure within regions of Nb solid solution, can be considered as in-situ reinforced composites. Nb-18 at.%AI ingots were arc melted and heat treated to provide several microstructures. Small compact tension specimens were cracked in compression- compression cyclic loading and subsequently grown in tension-tension cyclic loading. Fatigue crack growth rates were found to be similar to crack growth through a TiAI-based alloy with a lamellar microstructure. Threshold stress intensity factor was estimated as 5.3 MPaȡm, and fracture toughness as about 10 MPaȡm.