Many common engineering alloys are strengthened by precipitates with plate-like geometries. The mechanics of precipitation strengthening, while well resolved with spherical precipitates, are less well understood for plate-like geometries. In this work, we employ discrete dislocation dynamics simulations to study precipitation strengthening by ${\theta }^{\prime }$ precipitates in AlCu. We show that Orowan looping with parallel plate-like precipitates can be fundamentally different from spheres because it is governed by a steady-state glide process rather than a single critical dislocation geometry. We develop a model based on the formation of a dislocation dipole across the precipitate thickness to explain the observed strengthening. Finally, we show that while the precipitate misfit field can lead to both strengthening and weakening, strengthening is more common because of the steady-state process by which Orowan loops form.

许多常见的工程合金通过具有板状几何形状的沉淀物得到强化。沉淀强化的机制虽然很好地解决了球形沉淀物，但对于板状几何形状却不太了解。在这项工作中，我们采用离散位错动力学模拟来研究沉淀强化${\theta }^{‘}$在 AlCu 中析出。我们表明，具有平行板状沉淀物的 Orowan 循环可能与球体有根本的不同，因为它受稳态滑行过程而不是单个临界位错几何结构的控制。我们开发了一个基于在沉淀物厚度上形成位错偶极子的模型来解释观察到的强化。最后，我们表明虽然沉淀失配场可以导致强化和削弱，但由于 Orowan 环形成的稳态过程，强化更为常见。