In- and ex-situ study of the deformation behavior of the βo(ωo) phase in a Ti4Al3Nb alloy during high-temperature compression

Abstract

In-situ synchrotron-based high energy X-ray diffraction (HEXRD) and ex-situ Gleeble tests were conducted to investigate the deformation behavior of the β o (ω o ) phase in a Ti 4 Al 3 Nb alloy. In samples compressed at 600 and 800 °C, the brittle ω o phase deforms mostly elastically, resulting in the failure of the Ti 4 Al 3 Nb alloy by premature fracture. In a sample deformed at 900 °C, the ω o phase mostly transforms into the β o phase under uniaxial loading. Moreover, the ductility of a Ti 4 Al 3 Nb alloy is largely enhanced at this temperature. In a sample deformed at 1000 °C, dynamic recrystallization (DRX) of the β o phase extensively takes place. Direction 1 (D1) and Direction 2 (D2) deviating from the loading direction with an angle of 65° ± 5° and 15° ± 5° are selected to analyze the lattice strain evolution of (110) βo lattice planes. At the late stage of macro strain hardening, deformed<110> βo //D1 oriented grains bear a higher load due to the occurrence of DRX in<110> βo //D2 oriented grains. Subsequently, DRX continues in<110> βo //D1 oriented β o grains. The coordinated deformation of β o grains ensures the good deformability of a Ti 4 Al 3 Nb alloy at 1000 °C. • Cleavage fracture occurred for samples deformed below 800 °C due to the brittle nature of the ω o phase. • Reversal stress-induced ω o →β o transformation was observed at high applied stress. • Loads transfer among differently oriented β o grains was revealed.