Transition from dislocation glide to creep controlled damage in fatigued thin Cu films
Transition from dislocation glide to creep controlled damage in fatigued thin Cu films
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DOI：
10.1063/1.4819760
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发表时间：
2013-09
影响因子：
3.2
通讯作者：
C. Trinks;C. Volkert
中科院分区：
文献类型：
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作者：
C. Trinks;C. Volkert
采用基于原子力显微镜（AFM）的共振方法研究了40 ~ 360 nm铜膜的超高周疲劳行为。应变控制疲劳载荷下产生的损伤作为施加的应变，膜厚度，和循环次数高达5 × 1010的函数进行了研究。对于厚于100 nm的膜，挤出和边界裂纹限制了疲劳性能，但仅出现在所施加的应变幅度的阈值以上，该应变幅度与膜厚度的平方根成反比。挤压的形成归因于位错激活。在100 nm及更薄的薄膜中，晶界裂纹被晶界沟槽所取代。凹槽被认为是通过扩散介导的蠕变过程形成的，类似于在较高温度下的观察结果，但在这里由循环应力和毛细作用驱动，并且一旦累积的塑性应变超过临界值，凹槽就变得可检测。这些结果表明，由于…
The ultra-high cycle fatigue behavior of supported Cu films with thicknesses between 40 and 360 nm has been investigated using a novel atomic force microscope (AFM)-based resonance method. The damage created under strain controlled fatigue loading is investigated as a function of applied strain, film thickness, and cycle numbers up to 5 × 1010. For films thicker than 100 nm, extrusions and boundary cracks limit the fatigue performance but only appear above a threshold in the applied strain amplitude which scales inversely with the square root of the film thickness. The extrusion formation is attributed to dislocation activation. The grain boundary cracks are replaced by grain boundary grooves in films of 100 nm and thinner. The grooves are believed to form by diffusion mediated creep processes, similar to observations at higher temperatures but here driven by cyclic stresses and capillarity, and become detectable once the accumulated plastic strain exceeds a critical value. These results indicate that due...