Dislocation dynamics in a nickel-based superalloy via in-situ transmission scanning electron microscopy

The evolving landscape for alloy design

“…An example is shown in Figure 3b, where precipitate shearing and sequential fault creation/destruction events are captured in a STEM experiment. 82 Lab-scale x-ray tomography and ever-expanding synchrotron beamline facilities are revolutionizing our ability to collect 3D and 4D data. [83][84][85][86] In cases where higher resolution information about chemistry or microstructure is required, automated serial sectioning systems [87][88][89][90][91][92][93] can now collect such The 3D data set for a polycrystalline nickel-based superalloy (Figure 3b, center) was collected by the femtosecond laserassisted TriBeam tomography approach in 132 h. [94][95][96] The specific motivation for this data set was to extract 3D information on grain size and orientation and the connectivity of twinrelated grains, shown in a network representation (Figure 3b, bottom) for prediction of strength and fatigue behavior.…”

Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

“…The emergence of experimental techniques such as compression of micron-scale samples with nanoindentors [3][4][5][6] and high-resolution acoustic emission (AE) measurements of bulk samples [7] has revealed a novel paradigm: dislocation plasticity is a spatiotemporally fluctuating and intermittent process [8]. On micron scales, discrete strain bursts with a broad size distribution can be seen directly in the stress-strain curve [9][10][11][12].…”

Extracting information from noisy data: strain mapping during dynamic in situ SEM experiments

“…single crystals, individual precipitates or grain boundaries, it is still rarely utilized due to the challenging experimental conditions. However, in comparison to the frequently employed push-to-pull device method for tensile testing of individual manipulated, placed and fixed objects [8][9][10][11][12], the benefit of having multiple specimens besides each other is non-negligible [17]. While the easier experimental setup of in situ micropillar compression also allows for multiple specimens in one session, it suffers from the fact that due to the constraints from the tip and the base, the observed deformation behaviour is not always exclusively material-dependent [35,36].…”

“…While indentation based techniques, such as nanoindentation or micropillar compression, are by far the most common methods, tensile testing in such in situ setups has been conducted less frequently, as the experimental effort is considerably higher [6][7][8]. Independent of whether a push-to-pull geometry [8][9][10][11][12] or a gripping geometry [6,[13][14][15][16][17] is employed, the sample preparation is more tedious and the time required to conduct an experiment is distinctly longer compared to a single nanoindentation or microcompression test. Therefore, it is desirable to extract as much information as possible from such an individual tensile experiment.…”