December 2023 ESRFnews
15
DARK-FIELD X-RAY MICROSCOPY
Jon Cartwright
H U G H S I M O N S
diffracting volume, the recorded signal is weak, and
data collection slow. This is where the new EBS helps.
Its undulators that feed the insertion-device beamlines
generate harmonics with particularly narrow, symmetric
energy spreads. By selecting one of these harmonics, or
“pink beams”, rather than a monochromatic beam, it
is possible to extract even more flux than the EBS can
usually deliver. The result is a potential speed boost in
DFXM imaging by almost a factor of 100, enabling
better in situ studies and the investigation of materials
subject to even higher strain levels.
Thanks to the latest ERC backing for DFXM, this is
the goal now of ID03 scientist Can Yıldırım. Awarded
this year, Yıldırım’s ERC starting grant aims to establish
pink-beam DFXM (pDFXM), and to combine it in
the same instrument with 3DXRD, to add contextual
information about grains surrounding the main grain of
interest. The idea is to be able to create, for the first time,
a predictive model of how regions of metal components
can recrystallise during the various metallurgical steps
involved in their manufacture heating quenching
annealing rolling and so on
Recrystallisation in metals serves to enhance
their formability making them more amenable to
deformation But it can also be a big problem in certain
industries In turbine blades which are made of single
crystal metals for instance it is important that the
preferred crystalline axis is aligned with the blades
long axis as this is what gives a blade its strength
Recrystallisation can destroy this alignment making
the blades prone to failure but its origins are currently
impossible to pinpoint. “The problem is like finding
a needle in a haystack,” says Yıldırım. “On the surface,
you might see a small spot, something that suggests the
component has a flaw. But that spot might lead to some-
thing much bigger underneath – and where did it all
begin? The more we understand with new techniques is
that existing knowledge is wrong or misleading. If we can
have reliable models, we won’t have to test these things by
trial and error; we won’t have to put so much to waste.”
New lessons
With steel production accounting for 11% of global
CO
2
emissions, there is a big need for new lessons in
metallurgy. And there is much more besides steel. This
year, the ESRF joined nine other partners – including
Infineon Technologies, Germany’s largest semicon-
ductor manufacturer – in the €8m EU-funded project
AddMorePower to assist in the development of copper
interconnects for microelectronics in part via DFXM at
ID03 The ESRF receives over 09m
ID03 is due to begin user operation in March next
year and in fact most of the hardware is already in place
But there is still work to be done in particular on the
software and control side to make DFXM as user
friendly as possible Our dream is for a user to see a map
of grains click on one of them with the mouse and have
the instrument automatically realign itself to extract the
detailed data to reveal the strains and defects on that
specific grain says Detlefs
Figure 2 Dark-field X-ray microscopy maps a cross section of an embedded grain in barium titanate, a ferroelectric that finds application in specialist
capacitors and transducers in cars, computers and mobile phones. By imaging the grain while an electric field is applied across the material, Simons
and colleagues can see how the grain’s internal structure changes. An intensity map (left) reveals individual domains, while a map of reconstructed
strain (right) reveals the structural relationship between domain clusters.