Abstract In metallic materials, the activation of one slip system increases the flow strength of other slip systems, which is phenomenon known as latent hardening. This latent hardening behavior has been understood by the “forest hardening” mechanism arising from mutual dislocation interactions at the continuum length scale. As the size of a sample decreases to the submicron scale, the interactions between dislocations become increasingly sparse, so plastic deformation is instead governed mainly by dislocation sources. In this paper, we use three-dimensional dislocation dynamics (DD) simulations to examine plastic deformation in single crystalline Cu micropillars subjected to two types of combined loading conditions: tension after torsion and torsion after tension. These combined loadings are then compared with simple tension and pure torsion, respectively. We find that there exists a transition from latent hardening to latent softening in 600 nm samples undergoing tension after torsion. The systematic computational and theoretical model described here suggests explosive multiplication causes dislocation density to greatly increase, giving rise to latent softening in those micropillars under tension after torsion.

中文翻译：

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单晶FCC微柱在拉伸和扭转联合载荷下的潜在硬化/软化行为

摘要 在金属材料中，一种滑移系统的活化会增加其他滑移系统的流动强度，这种现象称为潜硬化。这种潜在的硬化行为已被连续长度尺度上相互错位相互作用产生的“森林硬化”机制所理解。随着样品尺寸减小到亚微米级，位错之间的相互作用变得越来越稀疏，因此塑性变形主要由位错源控制。在本文中，我们使用三维位错动力学 (DD) 模拟来检查单晶铜微柱在两种组合载荷条件下的塑性变形：扭转后的张力和张力后的扭转。然后将这些组合载荷与简单的张力和纯扭转进行比较，分别。我们发现在扭转后经受张力的 600 nm 样品中存在从潜在硬化到潜在软化的转变。这里描述的系统计算和理论模型表明，爆炸倍增会导致位错密度大大增加，从而在扭转后的张力下引起这些微柱的潜在软化。