To evaluate the effects of microstructural factors on the plastic behavior of Ti–6Al–4V alloys, micro-cantilevers featuring several grains were machined using a focused ion beam. The equiaxed structure (a mixture of equiaxed α phase and intergranular β phase) and bimodal structure (a mixture of an equiaxed α phase and lamellar phase) were examined to verify the microstructural effects. To determine the slip plane and direction, the crystal structure was evaluated using electron backscattered diffraction, following bending tests of the microcantilever. In addition, the elastic modulus and hardness of each grain were determined via nanoindentation testing. In the equiaxed microstructure, the β-phase deformation often occurred first; then, slips were activated inside the equiaxed α phase. It is concluded that the β phase deforms more easily than the α phase because the elastic modulus and hardness of the former are lower, as indicated by the nanoindentation testing. In the bimodal microstructure, β-lath deformation occurred along the acicular direction in the lamellar-phase region, and slips occurred inside the α grain. The deformation of the lamellar structure was associated with β-phase deformation and affected by the high local stress at the grain boundary and phase interface, owing to the difference in grain orientation within the lamellar structure. The results of this study suggest that the plastic behavior of Ti–6Al–4V alloys depends not only on the slip system of the α grains but also on the deformability of the β phase and the misorientation of adjacent grains in polycrystalline Ti–6Al–4V alloy.

为了评估微观结构因素对 Ti-6Al-4V 合金塑性行为的影响，使用聚焦离子束加工具有多种晶粒的微悬臂梁。检查等轴结构（等轴α相和晶间β相的混合物）和双峰结构（等轴α相和层状相的混合物）以验证显微结构效果。为了确定滑移平面和方向，在微悬臂梁的弯曲测试之后，使用电子背散射衍射评估晶体结构。此外，通过纳米压痕测试确定每个颗粒的弹性模量和硬度。在等轴组织中，β相变形往往最先发生；然后，在等轴α相内激活滑移。结论是β相比α相更容易变形，因为前者的弹性模量和硬度较低，如纳米压痕测试所示。在双峰组织中，层状相区沿针状方向发生β-板条变形，α晶粒内部发生滑移。由于层状结构内晶粒取向的差异，层状结构的变形与β相变形有关，并受到晶界和相界面处高局部应力的影响。本研究结果表明，Ti-6Al-4V 合金的塑性行为不仅取决于 α 晶粒的滑移系统，而且还取决于多晶 Ti-6Al-4V 中 β 相的变形能力和相邻晶粒的错误取向。合金。