In-situ observations of crack initiation and growth at notches in cast Ti-48Al-2Cr-2Nb

Gamma titanium aluminide alloys have recently received a great deal of attention due to their demonstrated potential for application in aircraft engines but there is little information on the early stages of crack initiation and growth. The objective of the study reported here was to observe the initial development of cracks at the scale of the microstructure. To accomplish this, in-situ straining experiments were conducted in tension under incremental loading conditions. To confine the processes of interest to well-defined regions, notched specimens were used. Observations regarding the initiation, growth and the influence of environment on failure are discussed.