Stability of disconnections in solute atmosphere

Disconnections, such as the disconnection dipole shown here from relaxed molecular dynamics simulations, are found on many grain boundaries and postulated to regulate boundary mobility. (b) An atomic-scale map of the segregation energy of dilute Ag atoms in a Cu matrix illustrating a zone of strong segregation (blue) for preferred solute occupancy.
Disconnections, such as the disconnection dipole shown here from relaxed molecular dynamics simulations, are found on many grain boundaries and postulated to regulate boundary mobility. (b) An atomic-scale map of the segregation energy of dilute Ag atoms in a Cu matrix illustrating a zone of strong segregation (blue) for preferred solute occupancy.

Scientists at Sandia created special diagrams to help understand how certain defects, called disconnections, behave in mixtures of two metals (called binary alloys) when temperatures and the amounts of different substances change. They used computer simulations to make a four-dimensional diagram that shows how these disconnections move based on the concentration of substances and the temperature.

They found three different ways that disconnections can move depending on how the substances group together at the defects:

  1. They move quickly when there are only a few extra substances around.
  2. They move slowly when there are a moderate number of substances grouped together.
  3. They don’t move at all when there are a lot of substances clustered together.

These diagrams help explain how the movement of disconnections is affected by the grouping of substances, showing a common pattern where substances can “pin” or hold back the movement of disconnections in different types of metal mixtures and at various grain boundaries.

Sandia experts linked to work

  • Douglas L. Medlin
  • Rémi Dingreville

Sponsored by

Department of Energy Office of Science logo

Publications

Hu, C., Medlin, D. L., and Dingreville, R. (2025) “Stability and mobility of disconnections in solute atmospheres: insights from interfacial defect diagrams,” Physical Review Letters 134, 016202. https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.016202


March 3, 2025