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arXiv 1902.09446cond-mat.mtrl-sci
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Mg中基位错与Mg $_{17}$ Al $_{12}$相相互作用的原子模拟

Atomistic Simulations of Basal Dislocations Interacting with Mg$_{17}$Al$_{12}$ Precipitates in Mg

Aviral Vaid, Julien Guénolé, Aruna Prakash, Sandra Korte-Kerzel, Erik Bitzek

摘要:

Mg $_{17}$ Al $_{12}$是Mg-Al合金中最主要的析出相,它对Mg-Al合金的力学性能有很大的影响。通过分子动力学和静力学模拟研究了基边和30个$^\text{o}$位错与Mg $_{17}$ Al $_{12}$沉淀的相互作用,改变了沉淀间距($L$)和沉淀尺寸($D$)、形状和取向。通过沉淀物阵列的临界分解剪切应力$τ_c$遵循通常的$\ln((1/D + 1/L)^{-1})$比例。在所有情况下,但最小的沉淀物,位错通过沉积在无序的相间边界的位错段,而不是剪切沉淀物或留在沉淀物周围的基质中的奥罗万环的障碍。吸收的位错也通过将位错段吸收到边界中来增加第二位错通过沉淀物所需的应力。用相同尺寸和形状的空隙代替沉淀物降低了临界通过应力和加工硬化贡献,而人工不可渗透的Mg $_{17}$ Al $_{12}$沉淀物增加了两者。这些见解将有助于改善非相干粒子硬化的介观模型。

英文摘要:

The mechanical properties of Mg-Al alloys are greatly influenced by the complex intermetallic phase Mg$_{17}$Al$_{12}$, which is the most dominant precipitate found in this alloy system. The interaction of basal edge and 30$^\text{o}$ dislocations with Mg$_{17}$Al$_{12}$ precipitates is studied by molecular dynamics and statics simulations, varying the inter-precipitate spacing ($L$), and size ($D$), shape and orientation of the precipitates. The critical resolved shear stress $τ_c$ to pass an array of precipitates follows the usual $\ln((1/D + 1/L)^{-1})$ proportionality. In all cases but the smallest precipitate, the dislocations pass the obstacles by depositing dislocation segments in the disordered interphase boundary rather than shearing the precipitate or leaving Orowan loops in the matrix around the precipitate. An absorbed dislocation increases the stress necessary for a second dislocation to pass the precipitate also by absorbing dislocation segments into the boundary. Replacing the precipitate with a void of identical size and shape decreases the critical passing stress and work hardening contribution while an artificially impenetrable Mg$_{17}$Al$_{12}$ precipitate increases both. These insights will help improve mesoscale models of hardening by incoherent particles.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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