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Micromechanics Facilities

Probing material properties at the micron scale requires dedicated machines and setups for sample manufacture, sample testing, and in situ as well as post mortem defect analysis. Within the past three years capabilities to produce and deform micron and submicron sized samples had been built up in the department Structure and Nano- Micromechanics:

The largest share of small scale samples at the MPIE is nowadays produced via a focused ion beam (FIB) based route, for which a Zeiss Auriga® Crossbeam system was installed in 2013. The FIB is operated with 5keV to 30keV Ga+ ions focused typically to a beamsize in the range of some nanometers. In contrast to standard FIBs, the attached nano patterning and visualization engine (NPVE, Fibics Inc, Ottawa, Canada) gives full access to the beam control. Thus, complex shapes with varying geometries requiring different dwell times locally can easily be set and manufactured in an automized way. By that, the NPVE helps us to surpass one of the bottle necks during micromechanical experiments: the manufacture of a statistically sound number of samples. Typical sample sizes produced via this route vary from several tens of nanometers up to 20 micrometer, which is in a size regime where a transition from a deterministic to a stochastic behavior is observed, and therefore a high number of experiments is required.

On top of the dedicated sample manufacture, also testing rigs spanning over several orders of magnitude had been implemented in past years. Our indentation systems are either able to operate at a synchrotron beamline without obstructing the x-ray beam, are operated inside a scanning electron microscope (SEM), or in the transmission electron microscope (TEM). The variety of testable sample sizes ranges from some tens of nanometers over several tens of micrometer to almost 500µm. The various new loading rigs provide significant overlap in maximum force and strain rate and complement the existing (macroscopic) straining rigs at the MPIE. Thus, we are now able to probe material´s response from the low nanometer regime up to macroscopic sample and component dimensions, giving us the unique ability to understand the material´s behavior across the relevant length scales.

All of the newly installed machines are aimed for in situ operation – i.e. advanced characterization tools as for instance the electron contrast channeling imaging (ECCI as pioneered in the MA department) or dedicated environmental loading conditions using a hydroelectric cell (in collaboration with the GO department) – and thus, are well suited for answering advanced questions in various material systems.

To increase the throughput of our testing facilities with additional environmental capabilities (e.g. gases, temperature) a chamber equipped with an optical microscope (Olympus DSX 500i) is being built within the next year.

Fig. 1   Asmec Unat II installed in a Jeol JSM 6490 SEM, our standard testing rig for micron sized samples. The counterparty (e.g. a diamond or tungsten tip) is marked with “Indentation”, with the sample support pin opposite of it. Sample and indenter can independently be moved along 4 axis with submicron resolution. In addition, the entire setup can be oriented with 5 additional axis, which allows for versatile experimental setups (EBSD, ECCI)
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