Robertson Stuart, Doak Scott, Sun Fu-Long, Liu Zhi-Quan, Liu Changqing, Zhou Zhaoxia
Department of Materials, Loughborough Materials Characterisation Centre, Loughborough University, Loughborough, U.K.
Wolfson School of Mechanical, Electrical and Manufacture Engineering, Loughborough University, Loughborough, LE11 3TU, U.K.
J Microsc. 2020 Sep;279(3):212-216. doi: 10.1111/jmi.12868. Epub 2020 Feb 18.
A site-specific xenon plasma focused ion beam preparation technique for microcantilever samples (1-20 µm width and 1:10 aspect ratio) is presented. The novelty of the methodology is the use of a chunk lift-out onto a clean silicon wafer to facilitate easy access of a low-cost probe type indenter which provides bending force measurement. The lift-out method allows sufficient room for the indenter and a line of sight for the electron beam to enable displacement measurement. An electroplated nanotwinned copper (NTC) was cut to a 3 × 3 × 25 µm microbeam and in situ mechanically tested using the developed technique. It demonstrated measured values of Youngs modulus of 78.7 ± 11 GPa and flow stress of 0.80 ± 0.05 GPa, which is within the ranges reported in the literature. LAY DESCRIPTION: In this paper a site specific method is present for making particularly small mechanical tests samples, of the order of 100 the size of a human hair. These small samples can then be used to determine the mechanical properties of the bulk material. Copper with a nano twinned grain structure is used as a test medium. Ion milling was used to cut the sample to shape and a micro probe was used for mechanical testing. Ion milling can cut away very small volumes of material as it accelerates ions at the surface of the sample, atomically machining the sample. Micro probes are a cost-effective small-scale load measurement devices, however, they require a large area for accessing the sample. The indenter requirements are a problem when making you samples with ion milling as ion millers are best at making small cuts. Our aim was to design a cutting strategy which reduces the amount of cutting required while allowing samples to be fabricated anywhere on the sample. We used a chunk lift out technique to remove a piece of material which is then welded to a wafer of silicon this gives sufficient space around the sample for ion milling and testing. The additional space allowed easy access for the probe. A 3 × 3 × 10 µm micro cantilever beam was cut out from copper, this beam was then bent. The force from bending and distance bent was measured and converted into Youngs modulus which is a measure of flexibility. The modulus value measured was comparable to the values reported in other papers.
本文介绍了一种用于微悬臂梁样品（宽度为1 - 20微米，长宽比为1:10）的特定位置氙等离子体聚焦离子束制备技术。该方法的新颖之处在于，将一块样品取出并放置在干净的硅片上，以便低成本的探针式压头能够方便地进行弯曲力测量。取出法为压头提供了足够的空间，并为电子束提供了视线，以实现位移测量。将电镀的纳米孪晶铜（NTC）切割成3×3×25微米的微梁，并使用所开发的技术进行原位力学测试。结果表明，测量得到的杨氏模量值为78.7±11吉帕，流动应力为0.80±0.05吉帕，均在文献报道的范围内。
本文介绍了一种特定位置的方法，用于制作特别小的机械测试样品，其尺寸约为人发的1/100。然后可以使用这些小样品来确定块状材料的力学性能。具有纳米孪晶结构的铜用作测试介质。使用离子铣削将样品切割成所需形状，并使用微探针进行力学测试。离子铣削通过加速样品表面的离子来切割掉非常小体积的材料，从而对样品进行原子级加工。微探针是一种经济高效的小规模载荷测量装置，然而，它们需要较大的区域来接触样品。在使用离子铣削制作样品时，压头的要求是一个问题，因为离子铣削最擅长进行小切割。我们的目标是设计一种切割策略，减少所需的切割量，同时允许在样品的任何位置制造样品。我们使用了整块取出技术来移除一块材料，然后将其焊接到硅片上，这为样品周围提供了足够的空间用于离子铣削和测试。额外的空间便于探针的使用。从铜中切割出一个3×3×10微米的微悬臂梁，然后对该梁进行弯曲。测量弯曲力和弯曲距离，并将其转换为杨氏模量，杨氏模量是柔韧性的一种度量。测量得到的模量值与其他论文报道的值相当。
