Microstructural evolution resulting from different deformation mechanisms of a high-Nb-containing TiAl alloy with harmonic structure during elevated-temperature deformation

A Ti-42.5Al-8Nb-0.2W-0.2B-0.1Y (at%) alloy with a harmonic structure was deformed via compression (temperature: 950 °C–1050 °C, strain rate: 10 ⁻² s ⁻¹ –10 ⁻⁴ s ⁻¹ ) and the resulting microstructure was characterized. The results revealed that at certain temperatures and strain rates the alloy undergoes compression deformation via intragranular deformation. However, with increasing temperatures and decreasing strain rates, this mechanism changed to grain boundary sliding (GBS) of β/B2 grains and γ grains in the enlarged shell area and the accommodated intragranular deformation of γ grains in the core area.