Effect of thermomechanical processing on microstructure characteristics of γ-TiAl-based alloy

Abstract

In this study, the grain boundary character distribution (GBCD) of the γ-TiAl-based alloy was modified through the thermomechanical processing route. A compression test was conducted to identify the mechanical property improvements based on the grain boundary engineering (GBE) treatment. After multidirectional isothermal forging (MDIF) and annealing, the average grain size was refined to 20 µm. The length ratio of the low Σ (1 ≤ Σ ≤ 29) coincidence site lattice (CSL) boundaries increased to 64.01%, with the alloy exhibiting a higher compressive strength (2913 MPa) and maximum compression ratio (45.3%), owing to the strengthening mechanism of grain boundaries and dislocations. Consequently, the combination of MDIF and annealing could be used for grain refinement and tuning GBCD of γ-TiAl-based alloys.