Influence of grain size on tensile properties and fracture toughness of TiAl based alloy

The influence of grain size and microstructure type on the ductility and fracture toughness of the alloy were systematically characterized. Results indicate that ductility depends on the grain size which determines ultimate strength in fully lamellar, duplex, and near gamma structures, and that both of these mechanical properties appear independent of the type of the microstructure under the condition of same grain size. However, yield strength depends on both grain size and microstructure types; as the grain size increases, fracture toughness of the alloy increases. It was also noticed that, for a given grain size, fracture toughness increases as the proportion of the lamellar structure increases. A fully lamellar structure with a relatively small grain size offers an optimal combination of ductility and fracture toughness