Tensile behavior and deformation mechanism for Ti–22Al–25Nb alloy with lamellar O microstructures

Abstract

In this research, the tensile behavior and deformation mechanism of two microstructures for Ti–22Al–25Nb alloy are studied by in-situ tensile test and electron backscatter diffraction (EBSD) experiment. Due to the higher B2 phase content and the long and continuous slip line, the solution-treated microstructure has better plasticity. For the aged microstructure, the slip line is short and scattered due to the obstruction of acicular O phase, which leads to the higher strength. In addition, the slip mode of B2 phase includes single system slip, double system slip and cross slip. {110}<111> slip and {112}<111> slip for B2 phase can be activated at room temperature. Meanwhile, the potential slip systems of O phase are summarized. The slip mode of O phase includes single system slip and double system slip, and the former is the most important one. All three types of slip systems (prism ‘a’ slip, basal ‘a’ slip, and pyramidal ‘c+a’ slip) for O phase can be activated at room temperature. Moreover, there is a good slip transmission between B2 and O phases. B2 phase slip can induce single system slip and double system slip of O phase. The Burgers orientation relation (BOR) between B2 and O phases is conducive to the slip transmission.