Magnetic interactions and Heisenberg model (CEA Saclay/French national research agency)

According to RKKY model, the energy due the spins of the conduction electrons of two atoms can be calculated by taking their product, as the spin of the one atom acts as effective magnetic field on the other atom. The simplified model which describes this phenomenon is the Heisenberg model, which has been extensively used and studied, in the case of pure elements. If there are impurities, however, the problem becomes much more complicated, as the periodicity of the structure gets lost.

Manganese segregation around dislocations (University of Illinois)

In order to produce stiff and flexible steels, a certain amount of manganese atoms are inserted into the material. Through the vacancy diffusion mechanism, these atoms segregate towards structural defects such as dislocations or grain boundaries. It is thought that the segregation of Mn atoms towards the structural defects would embrittle the material. Even though a microscopic analysis is required, due to the magnetic complexity caused by the Mn atoms, a straight forward understanding cannot be obtained via atomistic methods.

Carbon Cottrell atmospheres (University of Lyon, INSA de Lyon)

Over the course of the human history, it is known that the amount of C atoms inside steel is crucial in order to change its mechanical properties. This is because the C atoms, whose solubility is virtually zero in pure iron at room temperature, segregate towards structural defects, such as dislocations. This is thought to be provoked through the stress field created through the dislocations, which are a source of strong distortion in the Fe matrix.

Internal friction of composite iron (Yonsei university)

Stabilization of grain boundaries by solute pinning (University of São Paulo)