论文标题
添加性生产的铜微柱的异常高应变速率压缩行为
Anomalous High Strain Rate Compressive Behavior of Additively Manufactured Copper Micropillars
论文作者
论文摘要
微观动态测试对于在相关应变速率下对材料行为的理解至关重要。然而，尽管进行了二十年的激烈的微观力学研究，但微观金属的测试在很大程度上仅限于准静态应变率。在这里，我们报告了原始3D打印铜微柱的动态压缩测试，应应变率从$ \ sim0.001 $ s $ s $ s $^{ - 1} $到$ \ sim500 $ s $ s $ s $^{ - 1} $。据确定，微晶铜微柱以单剪切的方式变形，在所有应变速率下表现出弱应变率的依赖性。然而，超铁颗粒（UFG）铜微柱通过桶形通过枪管均匀变形，并以最高$ \ sim0.1 $ s $ s $ s $ s $^{ - 1}的应变速率显示出强的速率和较小的激活量，这表明脱位成核作为变形机制。在较高的应变速率下，屈服应力显着饱和，从而导致应变率敏感性降低了两个数量级和激活量增加四倍，这意味着变形机制过渡到集体脱位成核。
Microscale dynamic testing is vital to the understanding of material behavior at application relevant strain rates. However, despite two decades of intense micromechanics research, the testing of microscale metals has been largely limited to quasi-static strain rates. Here we report the dynamic compression testing of pristine 3D printed copper micropillars at strain rates from $\sim0.001$ s$^{-1}$ to $\sim500$ s$^{-1}$. It was identified that microcrystalline copper micropillars deform in a single-shear like manner exhibiting a weak strain rate dependence at all strain rates. Ultrafine grained (UFG) copper micropillars, however, deform homogenously via barreling and show strong rate-dependence and small activation volumes at strain rates up to $\sim0.1$ s$^{-1}$, suggesting dislocation nucleation as the deformation mechanism. At higher strain rates, yield stress saturates remarkably, resulting in a decrease of strain rate sensitivity by two orders of magnitude and a four-fold increase in activation volume, implying a transition in deformation mechanism to collective dislocation nucleation.
