An investigation of the fatigue and fracture behavior of multicomponent Nb-11Al-41Ti-1.5Mo-1.5Crintermetallic

This paper presents the results of a recent study of the fracture and fatigue crack growth behavior of a newly developed multicomponent niobium aluminide intermetallic Nb-11Al-41Ti-1.5Mo-1.5Cr alloy (compositions quoted in at % unless stated otherwise). The alloy is shown to have attractive combinations of room-temperature tensile ductility (approx. 11%) and fracture toughness (approx. scds 83 MPa\(\sqrt m \)) in the as-forged condition. However, the tensile properties and fracture toughness are degraded somewhat by direct aging at 750 °C for 25 h. The direct aged Nb-11Al-41Ti-1.5Mo-1.5Cr intermetallic is also shown to have comparable fatigue crack growth resistance to pure Nb, IN 718 and mill annealed Ti-6Al-4V at room- and elevated-temperature. Fatigue and fracture mechanisms are elucidated prior to a discussion of the implications of the current results for potential high temperature structural applications.