Phase-field study on the segregation mechanism of Cr to lamellar interface in C40-NbSi2/C11b-MoSi2 duplex silicide

TL;DR

This study uses a phase-field model incorporating first principles calculations to investigate how chromium segregates at lamellar interfaces in duplex silicides, revealing the importance of chemical interactions and temperature effects.

Contribution

The paper introduces a phase-field model that accounts for chemical and elastic interactions, highlighting the role of temperature-dependent chemical interactions in Cr segregation.

Findings

Cr segregation occurs with chemical interaction but not with elastic interaction alone.

Segregation magnitude depends on segregation energy evaluated with lattice vibrations.

Temperature effects are crucial for accurate modeling of Cr segregation.

Abstract

Cr-segregation to a lamellar interface in NbSi2/MoSi2 duplex silicide has been examined by a newly developed phase-field model. The model can take into account the segregation energy evaluated by a first principles calculation to reflect the chemical interaction between solute atoms and the interface in addition to the elastic interaction. Cr segregation occurs at the interface in the case with segregation energy whereas no segregation occurs in the case with only elastic interaction. However, the segregation is much smaller than that observed in the experiment when the segregation energy was evaluated by the first principles calculation without lattice vibration (i.e. for 0 K). Another simulations with the segregation energy with lattice vibration results in segregation comparable to that in the experiment. Thus, it has been revealed that the solute-interface chemical interaction and its temperature dependence is responsible for the interfacial segregation of Cr.