Electronic structure methodologies (density functional and tight
binding theories) from solid state physics are being applied to
the simulation of processes in theoretical physical
metallurgy. These include
fracture of metals
phase stability and surface structure in metals and ceramics
properties of defects, especially grain boundaries and their
role in structure property relations.
Current and future projects are aimed at
the simulation and understanding of hydrogen induced fracture in
iron and steel
simulations of grain boundaries in ferroelectric materials
the surface structure of ceramics
The latter links in to current and planned projects in oxide supported
transition metal catalysts and the role of water and electrical
overpotential in environmentally assisted cracking.
Atomistic simulation of the superalloy titanium aluminide
We have used a quantum mechanical prescription for the
calculation of interatomic forces. The image shows a
mechanical twin impinging upon a lamellar grain boundary.
Under mechanical loading the boundary prevents growth of
the twin into the next layer; however the applied stress
has caused a twinning dislocation to be nucleated and
emitted into the adjoining grain.
The minimum energy path for a hydrogen atom becoming trapped at
a vacancy in Fe, there being already two H atoms trapped there.
It is thought that this is a pivotal process in the diffusion
and trapping of hydrogen in high strength steels.
Work funded by the EU-FP7 programme MultiHy
Ivaylo Katzarov and Anthony Paxton, Physical Review Letters, 104 225502 (2010)
