Enhancing the mechanical properties of TWIP alloys by generalized stacking fault energy engineering

Modern structural parts must meet increasingly stringent requirements, encompassing not only mechanical performance but also considerations such as life cycle, processability, and ethical sourcing of raw materials. The twinning induced plasticity (TWIP) mechanism can enhance the strain hardening of metallic materials, which helps to improve both strength and ductility, overcoming the typical trade-off between these two properties. While the benefits of deformation twinning are acknowledged, the limited understanding of some aspects of the TWIP effect hinders the development of new alloys with enhanced combinations of strength and ductility. To address these knowledge gaps, the present work focusses on the generalized stacking fault energy (GSFE), a critical material parameter that may impact the performance of TWIP alloys. On the one hand, this work highlights the complex relationship between alloy composition, intrinsic and extrinsic SFEs, and their correlation with mechanical properties by a database analysis approach. The database contains more than a thousand entries and gathers all SFE values measured by node as well as partial dislocation separation methods using transmission electron microscopy (TEM) as well as SFE values measured by diffraction. On the other hand, we propose a novel high-throughput approach to compute the GSFE (i.e. the unstable and stable intrinsic SFEs, the unstable and stable extrinsic SFEs, as well as the energies associated to HCP nucleation) based on state-of-the-art machine learning (ML) potentials. This new approach is also compared to a density functional theory (DFT) based approach. The combination of the database and GSFE computations offers a comprehensive methodology in order to offer guidelines for the discovery of novel strong and ductile TWIP alloys.

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Hilhorst, A., & et al. (2025). Enhancing the mechanical properties of TWIP alloys by generalized stacking fault energy engineering. ICSMA20, Kyoto, Japan. https://hdl.handle.net/2078.5/269707