A numerical model to describe the onset of tension twining in magnesium alloys, which incorporates the influence of nanoparticles and strain rate, is proposed. This model is employed in conjunction with crystal plasticity, to study the compressive flow stress of magnesium alloys at strain rates from 10⁻³/s to 10³/s. The results show negative strain rate sensitivity (SRS) for the flow stress during the initial phase of plastic deformation, which is consistent with experimental results. The influence of nanoparticles on restraining twinning is demonstrated to diminish with strain rate, and regarded as the underlying mechanism for the negative SRS. The combined effects of nanoparticle presence, strain rate, grain size and initial texture on the compressive flow stress of nanoparticle-reinforced magnesium alloys, are investigated using the proposed model. Grain size and texture are shown to affect the SRS significantly, and a critical grain size (i.e., ∼2 µm) is identified from the simulations. When grains are smaller than this critical value, a negative SRS is observed. When the initial texture is changed, the numerical results show a transition from a negative SRS to a positive one.

提出了一个描述镁合金中拉伸缠绕开始的数值模型，该模型结合了纳米粒子和应变率的影响。该模型与晶体塑性结合使用，研究镁合金在 10 ⁻³ /s 至 10 ^{3应变速率下的压缩流变应力}/秒。结果表明，塑性变形初始阶段的流变应力具有负应变率敏感性 (SRS)，这与实验结果一致。纳米粒子对抑制孪晶的影响被证明随着应变率的增加而减弱，并被视为负 SRS 的潜在机制。使用所提出的模型研究了纳米颗粒的存在、应变率、晶粒尺寸和初始织构对纳米颗粒增强镁合金压缩流变应力的综合影响。晶粒尺寸和纹理显示对 SRS 有显着影响，并且从模拟中确定了临界晶粒尺寸（即，~2 µm）。当晶粒小于该临界值时，会观察到负 SRS。当初始纹理改变时，