arXiv subjects

T. Vermeij

Publications and source records attributed to T. Vermeij.

5 recordsLinked to original sources

arXiv2025

SLIDE: Automated Identification and Quantification of Grain Boundary Sliding and Opening in 3D

Grain Boundary (GB) deformation mechanisms such as Sliding (GBS) and Opening (GBO) are prevalent in alloys at high homologous temperatures but are hard to capture quantitatively. We propose an automated procedure to quantify 3D GB deformations at the nanoscale, using a combination of precisely aligned Digital Image Correlation (DIC), electron backscatter diffraction, optical profilometry, and in-beam secondary electron maps. The framework, named Sliding identification by Local Integration of Displacements across Edges (SLIDE), (i) distinguishes GBS from GBO, (ii) computes the datapoint-wise measured in-plane displacement gradient tensor (from DIC), (iii) projects this data onto the theoretical GBS tensor to reject near-GB plasticity/elasticity/noise, and (iv) adds the out-of-plane step from optical profilometry to yield the local 3D GBS/GBO vector; automatically repeated for each $\sim$50nm-long GB segment. SLIDE is validated on a virtual experiment of discrete 3D sliding, and successfully applied to Zn-coated steel experiments, yielding quantitative GBS/GBO activity maps.

cond-mat.mtrl-sci↗

arXiv2024

+SSLIP: Automated Radon-Assisted and Rotation-Corrected Identification of Complex HCP Slip System Activity Fields from DIC Data

Identification of crystallographic slip in metals and alloys is crucial to understand and improve their mechanical behavior. Recently, a novel slip system identification framework, termed SSLIP (for Slip Systems based Local Identification of Plasticity), was introduced to leap from conventional trace-based identification to automated, point-by-point identification, exploiting the full deformation kinematics. Using sub-micron-scale Digital Image Correlation (DIC) deformation fields aligned to Electron Backscatter Diffraction (EBSD) data, SSLIP matches the measured in-plane displacement gradient tensor to the kinematics of the optimal combination of multiple slip system activities, at each DIC datapoint. SSLIP was demonstrated to be successful on virtual and experimental case studies of FCC and BCC metals. However, for more challenging HCP crystal structures, the complete identification of all slip systems was found to be more challenging, posing limitations on automation and flexibility. To extend the capabilities of SSLIP, we propose an extended framework, hereinafter referred to as the +SSLIP method, which includes (i) a preselection of slip systems using a Radon transform, (ii) robustness to measured rigid body rotation by simultaneous identification of the local rotation field, (iii) identification of the two best matching slip systems for each data point, and (iv) a procedure to determine groups of slip systems with in-plane displacement gradient tensors that cannot be discriminated. This procedure yields the full (HCP) slip system activity maps for every slip system in each grain. The resulting objective identification method does not rely on the Schmid factor to select which slip system is active at each point. We show how slip systems from multiple slip families are successfully identified on virtual and real experiments on a Zn polycrystalline coating.

cond-mat.mtrl-sci↗

arXiv2024

High-resolution numerical-experimental comparison of heterogeneous slip activity in quasi-2D ferrite sheets

The role of heterogeneity in the plastic flow of thin ferrite specimens is investigated in this study. This is done through a recently introduced quasi-2D experimental-numerical framework that allows for a quantitative comparison of the deformation fields of metal microstructures between experiments and simulations at a high level of detail and complexity. The method exploits samples that are locally ultra-thin ("2D") and hence have a practically uniform microstructure through their thickness. This allows testing more complex loading conditions compared to uniaxial micromechanical experiments while avoiding the complexity of an unknown subsurface microstructure, which limits comparisons between experiments and simulations in traditional integrated approaches at the level of the polycrystalline microstructure. The present approach enables to study the effect of microstructural features such as grain boundaries. To study the role of stochastic fluctuations, a constitutive model is employed which introduces random heterogeneity into a crystal plasticity model. A detailed analysis of the simulations is performed at the level of individual slip systems. Since both experimental and numerical results are susceptible to stochastic fluctuations, the outcomes of many simulations are compared to the experimentally obtained result. This comparison allows us to determine how a single experiment relates to an ensemble of simulations. Additionally, results obtained with a conventional crystal plasticity model are considered. The analysis reveals that the heterogeneity in the plasticity model is essential for accurately capturing the deformation mechanisms.

cond-mat.mtrl-sci↗

arXiv2023

Martensite plasticity and damage competition in dual-phase steel: A micromechanical experimental-numerical study

Martensite damage in Dual-Phase (DP) steel has been studied extensively, yet, the exact deformation mechanisms that trigger or inhibit damage initiation remain mostly unexplored. Whereas generally assumed to be hard and brittle, lath martensite in fact deforms in a highly anisotropic manner, showing large strains under favorable habit plane orientations, which is attributed both to the lath morphology and to so-called 'substructure boundary sliding'. Yet, the correlation (or interplay) between plasticity and damage in lath martensite has not received much attention. Therefore, we raise the question whether these soft martensite plasticity mechanisms can delay or even inhibit damage initiation. We analyze several 'damage-sensitive' martensite notches, {i.e. thin contractions of two martensite islands,} by combining several state-of-the-art experimental and analysis methods. Deformations are tracked in-situ at the nanoscale, aligned to detailed microstructure maps, and categorised, for each martensite variant, into habit plane or out-of-habit-plane slip. In these experiments, strong plasticity (>70%) is observed in martensite notches, enabled by slip along a favorably oriented habit plane, whereas damaged notches have unfavorably oriented habit planes, showing limited pre-damage strains (<10%), carried by out-of-habit-plane slip. Additionally, one-to-one experimentally based Crystal Plasticity (CP) simulations are performed in parallel, employing a recently introduced Enriched CP approach which models a soft plasticity mechanism on the variants' habit plane. The Enriched CP simulations show considerably lower hydrostatic stresses in non-damaged and plastically deforming notches, thereby revealing that the soft habit plane mechanism is key for introducing the high plastic anisotropy that can lead to the inhibition of martensite damage in highly strained martensite notches.

cond-mat.mtrl-sci↗

arXiv2022

Extensive anisotropic lath martensite plasticity in dual-phase steels: A numerical-experimental investigation

This work presents a detailed experimental-numerical analysis of a low-carbon dual-phase steel microstructure, revealing evidence of significant anisotropic plastic deformation in lath martensite. A careful determination of the habit plane orientations in the present martensitic variants demonstrates that the observed traces of plastic slip coincide with the directions of the corresponding habit planes. To study the local lath martensite plastic activity, a dedicated substructure-enriched crystal plasticity based model is exploited. Compared with conventional bcc crystal plasticity, the model incorporates an extra crystallographic slip plane containing 3 softer slip systems parallel to the habit planes to capture the role of habit-plane plasticity. Simulations reveal consistent strain localization patterns as those observed in the experiments, with most plasticity localized in the martensite packets with their habit plane oriented favorably with respect to the applied load. Based on these insights, recommendations for future martensite modelling strategies and potential improvements of steels are discussed.

cond-mat.mtrl-sci↗