Crystalline structure

Grand challenges in materials science include the accelerated design of materials with exceptional properties for use in applications that span from microelectronics to large structures used in airplanes. Examples of desired properties include high-strength and high-formability, resistance to creep, fatigue, radiation, and high-thermal loading. The design of materials that meet such properties requires integration of experiment, modeling, simulation and analysis across multiple scales: from DFT to macroscopic levels.

I will discuss recent progress and open
challenges in connecting the dynamics
of line defects to the large-scale evolution of
facets, which give rise to free boundaries,
on macroscopic crystal surfaces. At the microscale,
a large number of differential equations is invoked
for the positions of defects. At the macroscale, the surface
evolution is plausibly described by a Partial Differential
Equation (PDE) for the surface height profile. A goal is to
derive boundary conditions for the PDE consistent with

Crystalline materials such as most metals, ceramics, rocks, drugs, and bones are composed of a 3D space-filling network of small
crystallites r the grains. The geometry of this network governs a range of physical properties such as hardness and lifetime before
failure. Our group has pursued an experimental method r 3DXRD r which for the first time enable structural characterisation of the
grains in 3D. Furthermore, changes in grain morphology can be followed during typical industrial processes such as annealing or
deformation.

Many materials (such as metals) are
polycrystals:
they consist of crystaline grains at various
orientations.
The interaction of these grains with X-rays can be
detected
as diffraction spots. Discrete tomography can be used
to
recover the internal oriention arrangement of the
grains
form such diffraction measurements.