Abstract Plastic deformation of sub-μm sized metals at different temperatures is influenced by factors absent in their bulk counterparts, including surface diffusion assisted softening and mechanical/thermal annealing-induced hardening. The test temperature and sample size therefore strongly affect the mechanical behavior, necessitating the construction of new deformation mechanism maps (DMM). Here, based on results from in situ quantitative compression tests on micro-pillars at various sizes and temperatures ranging up to 400°C, we have constructed DMMs for single-crystalline sub-micron-scale aluminum, consisting of elasticity, diffusive plasticity, and displacive plasticity regimes. In the sample size-stress DMM (for a fixed temperature), a “strongest size” is found at the triple junction of three regimes, above which “smaller is stronger”, below which “smaller is weaker”. In the diffusive plasticity regime, deformation is localized within the top pillar volume demarcated by a moving front interface, which is likely a newly formed grain boundary, that is impenetrable to impinging dislocations below a critical stress of ∼1 GPa.

中文翻译：

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亚微米尺寸铝的变形机制图

摘要 亚微米尺寸金属在不同温度下的塑性变形受其本体中不存在的因素影响，包括表面扩散辅助软化和机械/热退火诱导硬化。因此，测试温度和样品尺寸会强烈影响机械性能，需要构建新的变形机制图 (DMM)。在这里，基于对各种尺寸和温度范围高达 400°C 的微柱进行原位定量压缩测试的结果，我们构建了用于单晶亚微米级铝的 DMM，包括弹性、扩散塑性和位移塑性机制。在样品尺寸-应力 DMM（对于固定温度）中，在三个区域的三重结处发现了“最强尺寸”，高于该尺寸“越小越强”，低于这个“越小越弱”。在扩散塑性状态下，变形位于由移动前界面划定的顶部柱体积内，这可能是新形成的晶界，在~1 GPa 的临界应力以下冲击位错是无法穿透的。