4
M. P. Echlin et al.
ever much more advanced robotic polishing systems have been developed for
optical imaging [45] and electron microscopy [26–29]. Currently, cm 3 volumes have
been captured using the AFRL/RoboMet LEROY sectioning systems, as well as
entire turbine blade components [46] using manual polishing approaches. For SEM
imaging combined with robotic serial sectioning, the vacuum cycling and sample
transfer time sets a limit on the minimum cycle time, which makes experiments
with limited SEM imaging more time-consuming compared to other electron-opticsbased serial sectioning systems.
FIB and Xe-plasma FIBs (PFIB) are rather limited with respect to the total
accessible volume that can be analyzed as well as the types of material and speed
at which materials can be sectioned. Microtomes have been shown to be useful,
but primarily for biological samples and soft structural materials such as aluminum
and polymers, and microanalytical analysis is challenging due to the extreme
mechanical deformation imparted at the cut face.
X-rays have proven difficult to access large volumes of material with μm-scale
microstructural features, although the techniques for software reconstruction are
rapidly improving allowing access to deformed metallic samples [47, 48] and in situ
dislocation imaging [49]. The advantages of X-ray diffraction contrast tomography
(DCT) and the TriBeam femtosecond laser-based technique can be found elsewhere
[50]. The resolution of synchrotron DCT and the high energy diffraction microscopy
(HEDM) have dramatically improved [47], especially due to new reconstruction
algorithms that identify grains and diffraction spots. These codes are actively being
improved by the growing community of DCT users and scientists, facilitated by the
open repositories at the beamlines and the open-sourced nature of the code. Routine
access to synchrotron facilities can be challenging and requires careful preparation,
motivating efforts for the development of a range of lab-based X-ray techniques that
can be made available more broadly and with short notice. The available lab-scaled
DCT systems [51, 52] are most effective for in situ experiments on materials with
coarser grains than those accessible by synchrotron X-ray diffraction experiments
and mostly for undeformed samples; however the reconstruction codes and scanning
speeds are improving rapidly.
3 The TriBeam
The TriBeam microscope, shown in Fig. 2, is a modified FEI/Thermo Fisher
Scientific Versa 3D focused ion beam scanning electron microscope (FIB-SEM)
designed for high-speed, low-damage, bulk (mm 3 -scaled) serial sectioning [24, 25].
A femtosecond laser beam has been incorporated into the FIB-SEM chamber
with scanning lens, optics, and an alignment system. Multimodal data may be
collected between material removal steps using a range of detectors for grain orientation information (electron backscatter diffraction – EBSD), chemical information
(energy dispersive X-ray spectroscopy – EDS), atomic density (backscatter electron
detector), and topographical and morphological information (secondary electron
M. P. Echlin et al.
ever much more advanced robotic polishing systems have been developed for
optical imaging [45] and electron microscopy [26–29]. Currently, cm 3 volumes have
been captured using the AFRL/RoboMet LEROY sectioning systems, as well as
entire turbine blade components [46] using manual polishing approaches. For SEM
imaging combined with robotic serial sectioning, the vacuum cycling and sample
transfer time sets a limit on the minimum cycle time, which makes experiments
with limited SEM imaging more time-consuming compared to other electron-opticsbased serial sectioning systems.
FIB and Xe-plasma FIBs (PFIB) are rather limited with respect to the total
accessible volume that can be analyzed as well as the types of material and speed
at which materials can be sectioned. Microtomes have been shown to be useful,
but primarily for biological samples and soft structural materials such as aluminum
and polymers, and microanalytical analysis is challenging due to the extreme
mechanical deformation imparted at the cut face.
X-rays have proven difficult to access large volumes of material with μm-scale
microstructural features, although the techniques for software reconstruction are
rapidly improving allowing access to deformed metallic samples [47, 48] and in situ
dislocation imaging [49]. The advantages of X-ray diffraction contrast tomography
(DCT) and the TriBeam femtosecond laser-based technique can be found elsewhere
[50]. The resolution of synchrotron DCT and the high energy diffraction microscopy
(HEDM) have dramatically improved [47], especially due to new reconstruction
algorithms that identify grains and diffraction spots. These codes are actively being
improved by the growing community of DCT users and scientists, facilitated by the
open repositories at the beamlines and the open-sourced nature of the code. Routine
access to synchrotron facilities can be challenging and requires careful preparation,
motivating efforts for the development of a range of lab-based X-ray techniques that
can be made available more broadly and with short notice. The available lab-scaled
DCT systems [51, 52] are most effective for in situ experiments on materials with
coarser grains than those accessible by synchrotron X-ray diffraction experiments
and mostly for undeformed samples; however the reconstruction codes and scanning
speeds are improving rapidly.
3 The TriBeam
The TriBeam microscope, shown in Fig. 2, is a modified FEI/Thermo Fisher
Scientific Versa 3D focused ion beam scanning electron microscope (FIB-SEM)
designed for high-speed, low-damage, bulk (mm 3 -scaled) serial sectioning [24, 25].
A femtosecond laser beam has been incorporated into the FIB-SEM chamber
with scanning lens, optics, and an alignment system. Multimodal data may be
collected between material removal steps using a range of detectors for grain orientation information (electron backscatter diffraction – EBSD), chemical information
(energy dispersive X-ray spectroscopy – EDS), atomic density (backscatter electron
detector), and topographical and morphological information (secondary electron