Effect of strain rate and temperature on the deformation behavior in a Ti-23.1Nb-2.0Zr-1.0O titanium alloy

The compression behavior of a Ti-23.1Nb-2.0Zr-1.0O (at.%) alloy was investigated at strain rates from 0.1 s⁻¹ to 1000 s⁻¹ and temperatures from 100 °C to 200 °C on a Gleeble 3800 system and Split Hopkinson Pressure Bar (SHPB) compressive tester. Optical microscopy, electron backscatter diffraction (EBSD), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to characterize the microstructure evolution during the deformation. Numerous deformation phenomena, including dislocation slip, twinning of both {332}〈113〉 and {112}〈111〉 modes, stress-induced α” martensite (SIMα”) and stress-induced ω (SIω) transformations, were observed. The preferred activation of twinning and SIω transformations was observed in the sample compressed at lower temperatures and/or higher strain rates. The underlying mechanism is that twinning and stress induced phase transformations are attribute to higher stress concentrations at β grain boundaries and additional energy supplied by a higher strain rate, as well as high stacking fault energy because of higher temperature.