Crack resistance behaviour of an intermetallic TiAlSiNb alloy at room temperature

The room temperature crack growth behaviour of a Ti-Al-Si-Nb alloy consisting of the two intermetalic phases (Ti, Nb)3(Al, Si) and (Ti, Nb)5(Si, Al)3 is investigated in the present paper. The material exhibits a heterogeneous disordered microstructure and fails in a brittle manner. Crack growth is associated with a pronounced crack resistance behaviour. For a sample of nominally identical specimens the R-curves scatter around a mean curve with a standard deviation which remains roughly constant as the crack grows. A natural extension of the bundle model introduced in a previous paper is used to simulate R-curves and their scatter is in reasonably good agreement with the experimental findings.