Effect of lamellar spacing on fatigue crack growth behaviour of a TiAl-based aluminide with lamellar microstructure

► We studied lamellar spacing on fatigue crack growth resistance in TiAl-based alloy. ► Increase in cooling rate decreases distance between α2 plates, i.e., lamellar spacing. ► Air-cooled specimen with fine lamellae exhibited superior resistance to crack growth. ► This is due to zigzag crack growth across fine plates by linking microcracking. ► In furnace-cooled specimen crack growth resistance was improved by extrinsic effects.