Generalized stacking fault energy of γ-Fe

Abstract

We investigate the generalized stacking fault energy (-surface) of paramagnetic -Fe as a function of temperature. At static condition, the face-centred cubic (fcc) lattice is thermodynamically unstable with respect to the hexagonal close-packed lattice, resulting in a negative intrinsic stacking fault energy (ISF). However, the unstable stacking fault energy (USF), representing the energy barrier along the -surface connecting the ideal fcc and the intrinsic stacking fault positions, is large and positive. The ISF is calculated to have a strong positive temperature coefficient, while the USF decreases monotonously with temperature. According to the recent plasticity theory, the overall effect of temperature is to move paramagnetic fcc Fe from the stacking fault formation regime ( K) towards maximum twinning ( K) and finally to a dominating full-slip regime ( K). Our predictions are discussed in connection with the available experimental observations.

Keywords:

• -Fe
• stacking fault energy
• plasticity

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Swedish Research Council, the Swedish Foundation for Strategic Research, the European Research Council, the Chinese Scholarship Council and the Hungarian Scientific Research Fund [grant number OTKA 84078], [grant number 109570]. Qing-Miao Hu thanks the financial support from the NSF of China under [grant number 51271181], [grant number 51171187] and the Chinese MoST under [grant number 2014CB644001].