Effect of electric current on microstructure and texture evolution of the Ti2AlNb alloy during hot deformation

Abstract

In this study, the stress-strain behavior of sintered Ti2AlNb alloy obtained at the temperatures of 980 °C and 1080 °C with a strain rate of 0.5 s−1 was investigated using compression tests under furnace heating and current heating. When deformed at 980 °C, the B2 phase texture orientation all exhibited //ND and //ND during current-assisted hot compression (CAHC) and furnace hot compression (FHC). With the deformation temperature increased to 1080 °C, the texture //ND gradually moved towards the texture direction during CAHC. The results were ascribed to the different microstructure evolution that dynamic globularization and DRX by electric current. It indicated that the current promoted the spheroidization of the O phase which did not change the texture orientation. However, as the temperature increased to 1080 °C, the current promoted dynamic recrystallization which resulted in big changes in B2 phase texture orientation. The current promoted the spheroidization of lath by accelerating the phase transformation of O→B2. The current affected the dynamic recrystallization (DRX) mechanisms by promoting the transformation of low-angle grain boundaries (LAGBs) into high-angle grain boundaries (HAGBs) through continuous absorption of dislocations. The true stain-stress curves indicated the reduction of the deformation resistance and enhancement of the deformability of the Ti2AlNb alloy, which was closely related to the microstructure evolution.

Keywords

• Ti2AlNb alloy
• Current-assisted hot compression
• Texture evolution
• Dynamic globularization
• Dynamic recrystallization