The interactions between a plate-like precipitate and two twin boundaries (TBs) ($\left\{10\overline{1}2\right\}$, $\left\{11\overline{2}1\right\}$) in magnesium alloys are studied using molecular dynamics (MD) simulations. The precipitate is not sheared by $\left\{10\overline{1}2\right\}$ TB, but sheared by $\left\{11\overline{2}1\right\}$ TB. Shearing on the (110) plane is the predominant deformation mode in the sheared precipitate. Then, the blocking effects of precipitates with different sizes are studied for $\left\{11\overline{2}1\right\}$ twinning. All the precipitates show a blocking effect on $\left\{11\overline{2}1\right\}$ twinning although they are sheared, while the blocking effects of precipitates with different sizes are different. The blocking effect increases significantly with the increasing precipitate length (in-plane size along TB) and thickness, whereas changes weakly as the precipitate width changes. Based on the revealed interaction mechanisms, a critical twin shear is calculated theoretically by the Eshelby solutions to determine which TB is able to shear the precipitate. In addition, an analytical hardening model of sheared precipitates is proposed by analyzing the force equilibrium during TB-precipitate interactions. This model indicates that the blocking effect depends solely on the area fraction of the precipitate cross-section, and shows good agreement with the current MD simulations. Finally, the blocking effects of plate-like precipitates on the $\left\{10\overline{1}2\right\}$ twinning (non-sheared precipitate), $\left\{11\overline{2}1\right\}$ twinning (sheared precipitate) and basal dislocations (non-sheared precipitate) are compared together. Results show that the blocking effect on $\left\{11\overline{2}1\right\}$twinning is stronger than that on $\left\{10\overline{1}2\right\}$ twinning, while the effect on basal dislocations is weakest. The precipitate-TB interaction mechanisms and precipitation hardening models revealed in this work are of great significance for improving the mechanical property of magnesium alloys by designing microstructure.

板状沉淀物与两个孪晶界 (TB) 之间的相互作用 ($\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}$,$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$) 在镁合金中的研究使用分子动力学 (MD) 模拟。沉淀物不被剪切$\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}$结核病，但被剪掉了$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$结核病。(110) 平面上的剪切是剪切沉淀物中的主要变形模式。然后，研究了不同尺寸沉淀物的阻塞效应$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$孪生。所有沉淀物均显示出阻断作用$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$孪生虽然是剪切的，但不同尺寸析出物的阻挡作用不同。随着沉淀物长度（沿 TB 的面内尺寸）和厚度的增加，阻塞效应显着增加，而随着沉淀物宽度的变化而变化微弱。基于揭示的相互作用机制，通过 Eshelby 解从理论上计算临界双剪切以确定哪个 TB 能够剪切沉淀物。此外，通过分析 TB-析出物相互作用过程中的力平衡，提出了剪切析出物的分析硬化模型。该模型表明阻塞效应仅取决于沉淀物横截面的面积分数，并且与当前的 MD 模拟显示出良好的一致性。最后，$\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}$孪晶（非剪切沉淀），$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$孪晶（剪切沉淀物）和基底位错（非剪切沉淀物）一起比较。结果显示阻断作用对$\left\{11\overline{\mathrm{2个}}\mathrm{1个}\right\}$双胞胎比那强$\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}$孪生，而对基底位错的影响最弱。该工作揭示的析出物-TB相互作用机制和析出硬化模型对于通过微观结构设计改善镁合金的力学性能具有重要意义。