Effect of microstructure on the high-temperature deformation behavior of Ti-48Al-2W intermetallic compounds

The effect of microstructure on high-temperature deformation behavior of Ti-48Al-2W intermetallic compounds has been investigated in compressive tests performed at 1100 and 1200 degrees C. The microstructures were controlled as near gamma, duplex and near lamellar structure by heat treatments of cast ingots at 1250, 1300 and 1350 degrees C, respectively. The stress-strain curve exhibits a peak stress, which is followed by a gradual decrease into a steady state with increasing the strain. The peak flow stress was the highest in the near lamellar structure. The flow softening rate is higher in the near lamellar structure than that in the near gamma structure. The flow softening behavior of near gamma Ti-48Al-2W was due to a dynamic recrystallization of gamma grains. The flow softening behavior in near lamellar Ti-48Al-2W was occurred by kinking, rotating and globularization of lamellars. The flow localization and shear bands were observed in near lamellar structure during the high-temperature deformation. The flow localization parameters were calculated from the analysis based on the instability condition. The flow localization in the near lamellar structure was due to a higher flow softening rate. (C) 1999 Published by Elsevier Science S.A. All rights reserved.