Creep and fracture of structured nanocolumns grown on a substrate
Creep and fracture of structured nanocolumns grown on a substrate
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在基底上生长的结构化纳米柱的蠕变和断裂
DOI：
10.1016/j.mspro.2014.06.065
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
K. Minoshima
中科院分区：
文献类型：
--
作者：
H. Hirakata;T. Tagami;K. Minoshima
采用掠射角沉积法在硅衬底上生长了倾斜的钛纳米柱，对其室温蠕变断裂机理进行了研究。采用一种纳米柱阵列的实验方法，使用一个高2μm、宽2μm的微砖试件进行蠕变实验。为了弄清蠕变断裂是否以纳米尺度的应力集中为主，制备了两种类型的试件：正向试件(沿柱子倾斜方向加载)和反向试件(沿柱子倾斜方向加载)，其中反向试件在界面边缘的应力奇异性高于正向试件。在恒定的外力作用下，钛纳米柱以时间依赖的方式变形，然后在界面处断裂。对于相似的骨折寿命，正向试件比反向试件需要更大的作用力。采用有限元方法分析了蠕变试验过程中Ti/Si界面的局部应力分布。在具有相似断裂寿命的正向和反向试件中，在约5 nm区域边缘附近的Mise应力非常接近。这表明纳米尺度区域的局部应力场对蠕变断裂起主导作用。此外，与块体相比，纳米柱的室温蠕变速度大大加快。
The mechanics of room-temperature creep fracture on the nanoscale was evaluated on Ti oblique nanocolumns grown on a Si substrate using glancing angle deposition. An experimental method for the nanocolumn arrays using a micro-brick specimen (2 μm high and 2 μm wide) was used for the creep experiments. To clarify whether the nanoscale stress concentration dominated the creep fracture, two types of specimens were prepared: a forward specimen (loading with the column tilt direction) and a reverse specimen (loading against the column tilt direction), where the reverse specimen had a higher stress singularity at the interface edge than the forward specimen. The Ti nanocolumns deformed in a time-dependent manner under a constant applied force and then fractured at the interface. The forward specimens required a higher applied force than the reverse specimens for a similar fracture life. The local stress distribution along the Ti/Si interface during the creep experiments was analyzed using finite element method. The Mises stresses near the edge in the region of about 5 nm were very close in forward and reverse specimens with similar fracture lives. This suggested that the local stress field in the nanoscale region dominated the creep fracture. In addition, the room temperature creep of the nanocolumns greatly accelerated in comparison with their bulk counterparts.