The Role of Temperature and Magnetic Effects on the Stacking-fault Energy in Austenitic Iron

TL;DR

This study uses DFT and Monte Carlo methods to analyze how temperature and magnetic effects influence the stacking-fault energy in pure austenitic iron, revealing a strong magnetic dependence and an increase of SFE with temperature.

Contribution

It introduces a combined DFT and Monte Carlo approach to quantify the impact of magnetic effects and temperature on SFE in austenitic iron, which was not previously detailed.

Findings

SFE strongly depends on magnetic effects in pure iron.

SFE increases as temperature rises.

Magnetic excitations significantly influence SFE values.

Abstract

We have investigated the role of temperature and magnetic effects on the stacking-fault energy (SFE) in pure austenitic iron based on Density Functional Theory (DFT) calculations. Using the axial next-nearest-neighbor Ising (ANNNI) model, the SFE is expanded in terms of the free energiesof bulk with face-centered cubic (fcc), hexagonal close-packed (hcp), and double-hcp (dhcp) structures. The free-energy calculations require the lattice constant and the local magnetic moments at various temperatures. The earlier is obtained from the available experimental data, while the later is calculated by accounting for the thermal magnetic excitations using the Monte-Carlo tech- niques. Our results demonstrate a strong dependence of the SFE on the magnetic effects in pure iron. Moreover, we found that the SFE increases with temperature.