Impact of solutes on the lattice parameters and elastic stiffness coefficients of hcp Fe from first-principles calculations

Journal Article · 27 March 2019 · Computational Materials Science

DOI: https://doi.org/10.1016/j.commatsci.2019.03.056 · OSTI ID:1503323

Fellinger, Michael R. ^[1]; Hector, Jr., Louis G. ^[2]; Trinkle, Dallas R. ^[1]

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1. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
2. General Motors Global R&D Center, Warren, MI (United States)

The hexagonal close-packed (hcp) $$\epsilon$$-martensite phase in steels nucleates from the $$\gamma$$-austenite parent phase and can undergo further transformation to the $$\alpha'$$-martensite phase or exist as a metastable phase depending on temperature, mechanical loading, and alloy chemistry. The solute-dependent lattice parameters and elastic stiffness coefficients $$C_{ij}$$ of hcp Fe influence the mechanical properties of steels containing the $$\epsilon$$-martensite phase, as well as the martensitic transformations between the phases. We use density functional theory to calculate the lattice parameters and $$C_{ij}$$ of single-crystal hcp Fe as functions of solute concentration in the dilute limit for the substitutional solutes Al, B, Cu, Mn, and Si, and the octahedral interstitial solutes C and N. Our computationally efficient methodology separates the solute dependence of the $$C_{ij}$$ into lattice strain and chemical bonding contributions. The computed data can be used to estimate the effect of solutes on polycrystalline elastic moduli and the strain energy associated with martensitic transformations. In conclusion, the data can also serve as inputs to microstructure-based models of multiphase steels containing the $$\epsilon$$-martensite phase.

• Research Organization: Univ. of Illinois at Urbana-Champaign, IL (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0005976
• OSTI ID: 1503323
• Journal Information: Computational Materials Science, Vol. 164; Related Information: The raw and processed data required to reproduce these findings are available to download from http://hdl.handle.net/11256/982.; ISSN 0927-0256
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English