In-situ investigation of tensile behaviors of Ti–6Al alloy with extra low interstitial

Abstract

Abstract Tensile behaviors of Ti–6Al with extra low interstitial (ELI) have been systematically investigated using the in-situ tensile testing monitored by the scanning electron microscopy (SEM). The electron backscatter diffraction (EBSD) technique was employed to reveal the detailed deformation mechanisms during the in-situ tensile process. The results showed that multiple slip activities occurred during the in-situ tensile process. Moreover, prismatic and basal slips dominated the slip activities. To accommodate the increased macrostrain under the tensile loading, coordinated deformation mechanisms were involved in the tensile process, including crystalline orientation rotation, slip transmission and deformation twinning. α grains were rotated about 9.8 (±4)° for convenience of slip activation to accommodate the macrostrain when the tensile displacement reached to 0.4 mm. Slip transmission supplied the intergranular coordinated deformation which avoided the localized stress concentration at grain boundaries. Deformation twinning accommodated the intragranular strain in α grains with hard orientations. Furthermore, the mechanisms for microcrack formation was thoroughly investigated by combining the in-situ SEM observations with the EBSD technique. Localized stress concentration at the grain boundaries derived from the geometric incompatibility between neighboring α grains were mainly responsible for the microcrack formation in Ti–6Al ELI alloy.