Microstructural and textural evolution of high-purity titanium under dynamic loading

Abstract

The evolution of microstructure and texture during room temperature compression of high-purity titanium was studied under dynamic loading. X-ray diffraction (XRD) was used to examine the changes in the macrotexture while electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the microstructural evolution. Dynamic loading was found to enhance the activity of deformation twins; four types of primary twins were activated, including 101¯2, 112¯1, 112¯2 and 112¯4 twins. In addition, 112¯2–101¯2 and 101¯2–112¯2 secondary twins were also formed from a 10% thickness reduction. The newly formed [0001] TD orientation texture component was attributed to the 112¯2 primary twins. Although deformation twinning was the dominant deformation mechanism at the beginning of deformation, slip became dominant with increasing strain. Dislocations with Burgers vectors of ⟨c+a⟩ type character was predicted to accommodate strain along c-axis at higher deformation strain. The ⟨a⟩, pyramidal ⟨c+a⟩ and 112¯2–101¯2 secondary twins contributed to the formation of a basal texture at 40% thickness reduction. The twin boundary (TB) thickening resulted from a high density of dislocation interactions with the TB, which destroyed the misorientation relationship of the TB. The TB gradually evolved into TB segments or completely transformed into conventional high angle boundaries.