Crystallography and microstructure of the deformation bands formed in a metastable β titanium alloy during isothermal compression

Abstract

Abstract The plastic deformation of crystals accompanied by the formation of deformation bands or slip bands has been observed in previous studies; however, this phenomenon has not been examined in sufficient detail. In this study, the crystallography and microstructure of the deformation bands formed in a metastable β titanium alloy Ti–7Mo–3Nb–3Cr–3Al during isothermal compression were investigated. The obtained results revealed that numerous deformation bands were formed inside the β grains and along the initial β grain boundaries. The majority of the produced bands were located in the grain interiors, and their formation was accompanied by the fragmentation and spheroidisation of the lamellar α phase. According to the trace analysis results, these bands belonged to the {110} 1 ¯ 1> slip band type and exhibited high Schmid factors. The crystallographic calculation data indicated that the rotation axis of the misorientation between the β phase in the lamellar area and that in the band area passed through the deformation bands. Furthermore, the origin of the formation of bands was caused by the relative slip of the lamellar β and α phases due to the coordinated shear under compression. Thus, the findings of this study can help achieve a better understanding of the hot deformation mechanisms of titanium alloys.