The September 2011 journal club theme is “In-situ Studies in Mechanics”. The basic concept is to perform the experiments under a microscope, so that the typical quantitative information (stress, strain, crack length to name a few obvious ones) is augmented with real time microscopy output. The advantages are many-fold; (i) one can ‘see’ the deformation and failure process to reduce intelligent guesses in modeling (ii) experimental/boundary condition accuracy is enhanced, particularly for nanoscale specimens, (iii) access to various domains typically not considered by the mechanics community. The power of visualization actually goes beyond these three salient features, a vicarious example of which is the Journal of Visualized Experiments (). It is not really a mechanics journal, but the concept of expressing your thoughts and experiences with pictures and video boosts efficiency and liveliness in dissemination and learning instantly.
I am delighted to initiate this discussion by laying down few specific items that invite synergy as well as controversy. What I aim for this discussion is to bring up issues other than these, or at least to highlight the positives of in-situ studies, the associated ‘costs’ and whether it is worth doing as well as the future challenges. I have added a few references at the end of this posting for the zealous readers/participants. At the end of the month – I intend to follow up with a summary of your responses.
The Role Players: ‘In-situ Studies’ sounds like hardcore experimental research. However, the cream is rarely the experimental technique but the scientific finding. Perhaps the best players to stoke this area are the theoreticians/modelers who can challenge the experimentalists to support/refute their brain-childs. For example, dislocations were predicted and modeled long before they were seen – but the ability to see them made the transmission electron microscope the workhorse that it is. Being an experimentalist – I am eager to throw out the question: what are the outstanding issues in theory/modeling research that could be best addressed by in-situ studies? Or plainly describe a model or hypothesis of yours that you wish to be visualized in real time. What about other players – novel material synthesis, microscopy and miniaturization?
The Tools: Change the microscope and you change the mirror in the Kaleidoscope. Optical microscopy dominates the bio-materials research, but the low spatial resolution and surface-only probing might make it look less appealing for others. Yet, it could be the only tool to be equipped with really high speed cameras (and not to mention the largest possible work-volume to design the experimental setup). In-situ AFM type studies can provide premium resolution. On the other end, Transmission Electron microscopes (TEM) can visualize the internal features (dislocations, grain boundaries, voids – terms that directly relates to mechanics community) with up to atomic resolution. But the cost (not just monetary) has been pretty high. Not only drastic miniaturization is needed to measure anything useful but also the electron thin samples may show different behavior compared to the parent (exactly same bulk) material (analogous to forgetting to apply periodic boundary conditions in simulation?).
I am expecting a rich discussion on a plethora of issues including (i) whether or how important is the ‘real time microscopy’ for mechanics. Is conventional post mortem microscopy enough? Is in-situ straining (no stress or strain measurement) enough? (ii) is ‘seeing = believing’, or what else that we don’t see but is still there?, (iii) what are the undesired consequences of probing only very small volume of material? How can this be made up in the models (iv) what does the microscope itself do the specimen (irradiation/implantation)? (v) what are the challenges in sample preparation (such as, is the use of a focused ion beam safe?), (vi) how important it is to measure residual stress? (vii) how important is automated data collection? (viii) is there any way to improve the horrible temporal resolution of the visualization processes? I am certain there are many other concerns and I hope we are able tally and discuss as many as possible.
The Trades: Uniform tension, compression and nanoindentation are the two major types of experiments being performed. There is a remarkable lack in fracture, fatigue, creep as well as explicit interrogation of bi-material interfaces. Are there other pressing needs (for example – high or low temperature experiments?)
New Frontiers: Mechanics has seamlessly integrated phenomena that are non-mechanical in nature. Battery/Fuel cell/electro-chemistry; thermo-electrics/thermo-accoustics are just two (currently) high riding examples. However, in-situ studies on multi-domain are still rare. For example, in-situ STM or SThM studies could fundamentally advance our knowledge in strain dependence of electronic structure or thermal transport. I believe in-situ studies could gain a real cost-benefit edge by moving from tension/compression testing to multi-physics problems – where thermal, electrical, optical, magnetic, etc measurements could be made with the goal of tuning such with microstructure and deformation. For example, in-situ techniques can be particularly powerful for synthesis/growth reactor (example: =B099DRAX_X4&feature=related), or to study phase transformation. Another equally challenging (and rewarding) path is towards living cells, tissues and other bio-materials.
A.M. Minor, E.A. Stach, and J.W. Morris, Jr., “Quantitative in situ Nanoindentation in an Electron Microscope”, Applied Physics Letters, 79, no.11, (1625-1627) 2001.Haque, M., and Saif, M., 2002. In-situ tensile testing of nano-scale specimens in SEM and TEM. Experimental Mechanics 42, 123-128.
I. Chasiotis, W.G. Knauss, "A New Microtensile Tester for the Study of MEMS Materials with the aid of Atomic Force Microscopy", Experimental Mechanics 42 (1), pp. 51-57, (2002).
Y. Zhu, N. Moldovan and H.D. Espinosa. "A Microelectromechanical Load Sensor for In Situ Electron and X-Ray Microscopy Tensile Testing of Nanostructures," Applied Physics Letters, Vol. 86, No. 1, Art. No. 013506, 2005.
Wang ZL. 2011, Picoscale science and nanoscale engineering by electron microscopy. Journal of Electron Microscopy 2011;60:S269
Hosson JTM, Luysberg M, Tillmann K, Weirich T. Advances in transmission electron microscopy: in situ nanoindentation and in situ straining experiments, EMC 2008 14th European Microscopy Congress, September 2008, Aachen, Germany. Springer Berlin Heidelberg, 2008. p.463.
Eberl C, Saif T. In Situ Mechanical Testing of Biological and Inorganic Materials at the Micro- and Nanoscales. MRS Bulletin 2010;35:347.Legros M, Gianola DS, Motz C. Quantitative In Situ Mechanical Testing in Electron Microscopes. MRS Bulletin 2010;35:354.Li X, Chasiotis I, Kitamura T. In Situ Scanning Probe Microscopy Nanomechanical Testing. MRS Bulletin 2010;35:361.Spolenak R, Ludwig W, Buffiere JY, Michler J. In Situ Elastic Strain Measurements?Diffraction and Spectroscopy. MRS Bulletin 2010;35:368.Gai PL, Sharma R, Ross FM. Environmental (S)TEM Studies of Gas-Liquid-Solid Interactions under Reaction Conditions. MRS Bulletin 2008;33:107
Applications oriented papers:
Haque, M. A. & Saif, M. T. A., "Deformation Mechanisms in Free-standing Nano-scale Thin Films: A Quantitative In-situ TEM Study", Proceedings of the National Academy of Science, Vol. 101, No. 17, pp. 6335-6340, 2004.
Zhu, Y. and H.D. Espinosa, "An electromechanical material testing system for in situ electron microscopy and applications", Proceedings of the National Academy of Sciences of the United States of America, 2005. 102(41): p. 14503-14508.
Cumings J, Zettl A, Rotkin S, Subramoney S. Electrical and Mechanical Properties of Nanotubes Determined Using In-situ TEM Probes, in Applied Physics of Carbon Nanotubes. Springer Berlin Heidelberg, 2005. p.273.
Z.W. Shan, R.K. Mishra, S.A. Syed Asif, O.L. Warren and A.M. Minor, “Mechanical annealing and source-limited deformation in submicron-diameter Ni crystals”, Nature Materials, 7, no.2, (2008), p. 115-119
Oh SH, Legros M, Kiener D, Dehm G. In situ observation of dislocation nucleation and escape in a submicrometre aluminium single crystal. Nat Mater 2009;8:95.
Rajagopalan, J., C. Rentenberger, H. P. Karnthaler, G. Dehm, and M. T. A. Saif, "In situ TEM Study of Microplasticity and Bauschinger Effect in Nanocrystalline Metals," Acta Materialia, Volume 58, Issue 14, Pages 4772-4782, August 2010.
Zheng K, Wang C, Cheng Y-Q, Yue Y, Han X, Zhang Z, Shan Z, Mao SX, Ye M, Yin Y, Ma E. Electron-beam-assisted superplastic shaping of nanoscale amorphous silica. Nat Commun 2010;1:24.
Jian Yu Huang, Li Zhong, Chong Min Wang, John P. Sullivan, Wu Xu, Li Qiang Zhang, Scott X. Mao, Nicholas S. Hudak, Xiao Hua Liu, Arunkumar Subramanian, Hong You Fan, Liang Qi, Akihiro Kushima, Ju Li, “In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode”, Science 10 December 2010: vol. 330 no. 6010 pp. 1515-1520
Espinosa HD, Juster AL, Latourte FJ, Loh OY, Gregoire D, Zavattieri PD. Tablet-level origin of toughening in abalone shells and translation to synthetic composite materials. Nat Commun 2011;2:173.