Microstructure Evolution of a High Nb Containing TiAl Alloy with (α2 + γ) Microstructure during Elevated Temperature Deformation

Abstract

In order to verify the correctness of the transition of deformation mechanism with the change in deformation parameters and to reveal the types and mechanism of dynamic recrystallization of γ grains during compression deformation, microstructure characterization of Ti-43.5Al-8Nb-0.2W-0.2B (at. %) alloy after isothermal compression deformation were performed. When the alloy was deformed at 1000 • C/10 −2 s −1 , the initial γ grains are elongated and significantly refined and the fraction of low angle grain boundaries (LAGB) of γ grains is obviously increased and the texture intensity remains unchanged, which indicates that the compression deformation in dislocation creep region is dominated by intragranular deformation and dynamic recrystallization (DRX) of γ grains. Besides, the lattice rotation at grain boundary serrations may be responsible for the nucleation of new recrystallized γ grains, and the following growth process may be achieved by the migration of γ grain boundaries. However, when the alloy deformed at 1050 • C/10 −4 s −1 and 1000 • C/10 −4 s −1 , the γ grains maintain equiaxed shapes and distribute more uniformly and the fraction of LAGB of γ grains is slightly raised and the texture sharpness decreases, which indicates that the compression deformation in grain boundary sliding (GBS) region is mainly controlled by GBS of γ grains and DRX occurs simultaneously within some coarse γ grains.

Intermetallic Alloys

“…Among a number of TiAl based alloys, TiAl alloys with a (α 2 + γ) microstructure are known to be promising for high-temperature structural materials, such as aero components in air craft. On the Nb-containing TiAl with a (α 2 + γ) microstructure, Chu et al [5] demonstrated that a high temperature deformation mechanism changes the dislocation creep to grain boundary sliding. The editor believes that the characterization of microstructures and the assessment of the deformation mechanism of the relevant alloy should be useful for developing the aero components.…”

Effect of Microstructure on the High-Cycle Fatigue Behavior of Ti(43-44)Al4Nb1Mo (TNM) Alloys

“…Gamma TiAl-based alloys have been successfully applicated in aerospace and automotive industries after decades of developments [1][2][3]. In recent years, TiAl alloys containing a large amount of β-stabilizing elements, such as Nb and Mo, have attracted much more attentions due to their excellent elevated temperature properties [4][5][6][7]. Among them, the TNM alloy, which contains a balanced concentration of Nb and Mo, was recognized as the representative third generation TiAl alloy [8,9].…”

Diffusion Bonding of Ti2AlNb Alloy and High-Nb-Containing TiAl Alloy: Interfacial Microstructure and Mechanical Properties

“…As new lightweight and high-temperature structure materials, Ti 2 AlNb alloy and high-Nbcontaining TiAl alloys (abbreviated as TAN alloys) have received significant attention in the aerospace field [1][2][3]. The addition of the Nb element gives them excellent properties, such as low density, high specific strength, favorable oxidation, creep resistance [4], and especially high temperature properties.…”