Evolution of lamellar structure in Ti-47Al-2Nb-2Cr-0.2W alloy sheet

The Ti-47Al-2Nb-2Cr-0.2W alloy sheets were obtained by hot pack rolling. The as-rolled sheet has an inhomogeneous duplex microstructure composed of elongated gamma grains and lamellar colonies. Heat treatments were conducted on the as-rolled sheets. The results show that the microstructures with different sizes and grain boundary morphologies were developed after different heat treatments. A coarse fully lamellar structure can be refined if the heating time, together with the cooling rate, is appropriately controlled. The grain growth exponent is found to be approximately 0.2, and the activation energy of grain boundary migration of the alloy is around 225 kJ/mol.