Slip transfer behavior in Ti–2Al-2.5Zr titanium alloy under biaxial stress condition at room temperature and 350 °C

Biaxial tensile tests of Ti–2Al-2.5Zr titanium alloy were conducted at room temperature (RT) and 350 °C to systematically investigate the slip transfer effect between neighboring grains. The slip transfer behavior was analyzed based on the Global Schmid factor (GSF) and the geometric compatibility factor (m′). The results show that under RT biaxial deformation, slip system activation follows Schmid's law, leading to stochastic slip transfer characteristics governed by the slip systems activated in adjacent grains. At 350 °C, extensive dislocation slip accumulates near the grain boundaries of individual grains and “forces” neighboring grains to activate slip systems with high m′ values near the boundaries to accommodate the deformation, even when these slip systems exhibit low GSF values. Crystal plasticity finite element models (CPFEM) were constructed based on the real microstructure, with boundary conditions derived from scanning electron microscopy–digital image correlation (SEM–DIC) measurements to simulate biaxial deformation at RT and 350 °C. The simulation results demonstrate that stress concentration at the intersections of multiple grain boundaries is significantly higher than that at individual grain boundaries, which results in the accumulation of dislocation slip and severe concentration of deformation under biaxial tensile tests at 350 °C. The research findings of this paper are presented intuitively through SEM-DIC, and supported by the CPFEM simulation results.