Review and construction of interatomic potentials for molecular dynamics studies of hydrogen embrittlement in Fe─C based steels. Issue 13 (29th February 2020)

• Record Type: Journal Article
• Authors: Zhou, Xiaowang; Foster, Michael E.; Ronevich, Joseph A.; San Marchi, Christopher W.
• Is Part Of: Journal of computational chemistry. Volume 41:Issue 13(2020)
• Page Start: 1299
• Page End: 1309
• Publication Date: 2020-02-29
• Subjects: Fe─C steels -- hydrogen embrittlement -- interatomic potential -- mechanical properties -- molecular dynamics; Chemistry -- Data processing -- Periodicals; 542.85
• DOI: 10.1002/jcc.26176
• Languages: English
• ISSNs: 0192-8651

Abstract

Abstract: Reducing hydrogen embrittlement in the low‐cost Fe─C based steels have the potential to significantly impact the development of hydrogen energy technologies. Molecular dynamics studies of hydrogen interactions with Fe─C steels provide fundamental information about the behavior of hydrogen at microstructural length scales, although such studies have not been performed due to the lack of an Fe─C─H ternary interatomic potential. In this work, the literature on interatomic potentials related to the Fe─C─H systems are reviewed with the aim of constructing an Fe─C─H potential from the published binary potentials. We found that Fe─C, Fe─H, and C─H bond order potentials exist and can be combined to construct an Fe─C─H ternary potential. Therefore, we constructed two such Fe─C─H potentials and demonstrate that these ternary potentials can reasonably capture hydrogen effects on deformation characteristics and deformation mechanisms for a variety of microstructural variations of the Fe─C steels, including martensite that results from γ to α phase transformation, and pearlite that results from the eutectic formation of the Fe3 C cementite compound. Abstract : Our potentials enable molecular dynamics simulations of hydrogen embrittlement in Fe─C steels. The figure above shows simulated configurations after a tensile strain of 1.0 for a face centered cubic (fcc) iron with and without 5% hydrogen. In the figure, local fcc, bcc (body centered cubic), hcp (hexagonal closely packed), and undetermined structures are colored green, blue, red, and white respectively. The results indicated that hydrogen has a significant impact on deformation mode. Without hydrogen, deformation are mainly cause by slip as manifested by the formation of extensive hcp zones. With hydrogen, slip is inhibited as manifested by the formation of extensive distorted regions (white atoms).