Coherent Xray Scattering Studies of Phase Transitions in Metals Karl Ludwig, Boston University MET D

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Coherent X-ray Scattering Studies of Phase
Transitions in MetalsKarl Ludwig, Boston
UniversityMET DMR-0508630
The coherent visible light from lasers has long
been used to study how molecules move
(dynamics) on length scales comparable to or
larger than those of visible light. Powerful 3rd
generation synchrotron sources have only
relatively recently enabled such studies to be
performed with coherent x-rays. Because x-rays
have wavelengths much smaller than those of
visible light, this allows us to examine atomic
and molecular dynamics on nanometer length scales
much smaller than was previously possible. In
the results shown here, we are examining
microscopic reversibility in a shape memory alloy
and the kinetics of the underlying martensitic
phase transition in Cobalt.
Top rightCoherent scattering pattern from
nanocrystallites in a commercial shape-memory
alloy obtained using a 400 nm x-ry beam. Bottom
right Kinetics of the martensitic phase
transition between HCP and FCC structures in
Cobalt. Successive patterns are taken 140
seconds apart.
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Coherent X-ray Scattering Studies of Phase
Transitions in MetalsKarl Ludwig, Boston
UniversityMET DMR-0508630
Education and Outreach One graduate student
(Chris Sanborn) is currently working on this
program. In addition, a Boston University
undergraduate (Safa Alzaim) has also been
contributing to the project during part of her
time in our lab. Chris is obtaining an excellent
exposure to a broad range of topics in materials
science research within the context of an
international collaboration with the group of
Prof. Mark Sutton at McGill University, in
Montreal.
RightGraduate student Chris Sanborn with
coherent x-ray scattering system on beamline 8-ID
of the Advanced Photon Source at Argonne National
Laboratory.