Linear complexions: Metastable phase formation and coexistence at dislocations

TL;DR

This paper reports the discovery of a unique three-phase coexistence near dislocations in Fe-Ni alloys, revealing stable nanoscale precipitate arrays called linear complexions through atomistic simulations, and explaining their thermodynamics.

Contribution

It introduces the concept of linear complexions as stable nanoscale precipitate arrays along dislocations, expanding understanding of phase coexistence in Fe-Ni alloys.

Findings

Discovery of three-phase coexistence near dislocations

Observation of stable nanoscale precipitate arrays (linear complexions)

Thermodynamic explanation of metastable phase formation

Abstract

The unique three-phase coexistence of metastable B2-FeNi with stable L10-FeNi and L12-FeNi3 is discovered near edge dislocations in body-centered cubic Fe-Ni alloys using atomistic simulations. Stable nanoscale precipitate arrays, formed along the compression side of dislocation lines and defined as linear complexions, were observed for a wide range of compositions and temperatures. By analyzing the thermodynamics associated with these phase transitions, we are able to explain the metastable phase formation and coexistence, in the process defining new research avenues for theoretical and experimental investigations.