The high strength of Al-Li alloy is mainly attributed to precipitates, which has attracted extensive investigations on precipitation dynamics and interaction with dislocations. However, the influence of plate-like T₁ precipitate on mechanical anisotropy is still not fully clarified, and an accurate corresponding modeling framework considering inhomogeneous distribution and various configurations of T₁ precipitate is also needed. Here, the evolution of mechanical anisotropies in 2198 Al-Li alloy sheets is systematically studied with different distributions and thicknesses of T₁ precipitates obtained via changing pre-deformation direction and artificial aging temperature. A new modeling framework based on visco-plasitic self consistant (VPSC) is proposed to predict the anisotropic yield strength under different processing conditions. The resistance of four variants of T₁ precipitates which form a 'T₁ precipitate forest' to dislocation movement is considered. According to the geometric relationship with slipping systems, T₁ precipitates can be divided into three types: type I is parallel to slipping plane, type II is parallel to slipping direction but not slipping plane, and type III has a certain angle to both slipping plane and direction. The critical resolved shear stress (CRSS) of each slipping system can be calculated using a linear mixture law considering volume fraction and shear strength of these three types. It is found that T₁ precipitate of type I plays an important role in the strengthening of 2198 Al-Li alloy sheet. The shear strengths of types I, II and III are determined to be 400 MPa, 8 MPa and 8 MPa, respectively, at artificial aging temperature of 155 °C, and reach 400 MPa, 40 MPa and 40 MPa due to the increased T₁ thickness when aging temperature increases to 162 °C. The calculated anisotropy of yield strength is in good agreement with experimental results. Furthermore, a reasonable correlation between slipping activation and T₁ precipitate is revealed. That is, the activation fractions of different slipping systems exhibit how the varying distribution and thickness of T₁ precipitate lead to different mechanical anisotropy of 2198 Al-Li alloy sheet.

Al-Li合金的高强度主要归因于析出物，这引起了对析出动力学和与位错相互作用的广泛研究。然而，片状T ₁析出物对力学各向异性的影响仍未完全阐明，还需要考虑T ₁析出物的不均匀分布和各种构型的精确对应建模框架。_{在这里，系统地研究了不同分布和T 1}厚度下2198 Al-Li合金板的机械各向异性的演变。通过改变预变形方向和人工时效温度得到析出物。提出了一种基于粘塑性自洽 (VPSC) 的新建模框架来预测不同加工条件下的各向异性屈服强度。考虑了形成“T ₁沉淀森林”的四种T ₁沉淀变体对位错运动的抵抗力。根据与滑移系统的几何关系，T ₁析出物可分为三种类型：I型平行于滑移面，II型平行于滑移方向但不滑移面，III型与滑移面和方向都有一定的夹角。考虑到这三种类型的体积分数和剪切强度，可以使用线性混合定律计算每个滑移系统的临界分辨剪切应力 (CRSS)。发现I型T ₁析出物在2198铝锂合金薄板的强化中起重要作用。在人工时效温度为155℃时，I、II、III型的剪切强度分别确定为400 MPa、8 MPa和8 MPa，由于T _{1增加，剪切强度达到400 MPa、40 MPa和40 MPa}当老化温度增加到 162 °C 时的厚度。计算得到的屈服强度各向异性与试验结果吻合较好。_{此外，还揭示了滑移活化与 T 1}沉淀之间的合理相关性。即不同滑移体系的活化分数表现出不同的T ₁析出物分布和厚度如何导致2198 Al-Li合金薄板的不同机械各向异性。