Flow softening behavior during high temperature deformation of Ti-48Al-2W intermetallic compound

Abstract

The high temperature deformation behavior of Ti-48Al-2W intermetallic compound, having near gamma and near lamellar structure, was investigated by isothermal compressive tests at temperatures ranged 1100-1200 degrees C under strain rates ranged 10(-3)-10(-1) s(-1). The stress-strain curve exhibited a peak stress, and followed by a gradual decrease in flow stress into a steady state with inc;easing the strain. The peak now stress and the flow softening rate were higher in near lamellar structure compared to those in near gamma structure at a fixed strain. The flow softening was due to the dynamic recrystallization of gamma grains in near gamma structure. Whereas it occurred by kinking, rotating and globularization of lamellars in near lamellar structure. The flow localization and inhomogeneous shear bands were observed in near lamellar structure during the deformation. The now localization parameters were calculated from the instability condition which causes the localized deformation. The now localization is considered due to the higher flow softening rate in near lamellar structure.