TY - JOUR A1 - Maximilian, Thuy A1 - Spyrantis, Alexander A1 - Böhning, Martin A1 - Niebergall, Ute A1 - Maaß, Robert T1 - Spatially resolved roughness exponent in polymer fracture JF - Physical review materials N2 - The fracture surface of slow and continuous crack propagation during environmental stress cracking of a semicrystalline polyethylene exhibits isotropic roughness exponents at the local scale but resolved across the macroscopic fracture surface a clear position dependence is found. The spatially resolved roughness exponent admits values in the range between 0.1 and 0.4, demonstrating nontrivial exponents in the small length-scale regime. Instead, they vary across the fracture surface according to the stress-state distribution, which suggests that the exponents are intimately linked to the locally dominating dissipation processes during craze cracking. KW - Plasticity KW - Fracture KW - Material failure KW - Mechanical deformation PY - 2022 DO - https://doi.org/10.1103/PhysRevMaterials.6.L090601 VL - 6 IS - 9 SP - 1 EP - 7 PB - American Physical Society CY - USA, Maryland AN - OPUS4-55797 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ikeda, Yuki A1 - Mancias, J. A1 - Gan, B. A1 - Maaß, Robert T1 - Evidence of room-temperature shear-deformation in a Cu-Al intermetallic JF - Scripta Materialia N2 - Lamellar eutectics are known to evidence plastic shear in otherwise brittle intermetallics, if the lamella spacing is small enough. Here we pursue this idea of confined plasticity in intermetallics further and demonstrate room-temperature shear-deformation in a two-phase CuAl 2 -CuAl intermetallic nano- composite. The presence of a phase with a 3-fold symmetry is also revealed after deformation. Simula- tion of transmission electron microscopy images shows this to be monoclinic CuAl. These observations are made in the deformation zone underneath locations of nanoindents, of which the force-displacement curves exhibit an unusual response of continuously increasing pop-in sizes with load. KW - Nanoindentation KW - Intermetallic KW - Nano-composite KW - Shear bands KW - Plasticity PY - 2021 DO - https://doi.org/10.1016/j.scriptamat.2020.08.033 VL - 190 SP - 126 EP - 130 PB - Elsevier Ltd. AN - OPUS4-52455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Maaß, Robert A1 - Derlet, P. T1 - Micro-plasticity in a fragile model binary glass JF - Acta Materialia N2 - Atomistic deformation simulations in the nominally elastic regime are performed for a model binary glass with strain rates as low as 10 4 /s (corresponding to 0.01 shear strain per 1 μs). A strain rate dependent elastic softening due to a micro-plasticity is observed, which is mediated by thermally-activated localized structural transformations (LSEs). A closer inspection of the atomic-scale structure indicates the material response is distinctly different for two types of local atomic environments. A system spanning iscosahe- drally coordinated substructure responds purely elastically, whereas the remaining substructure admits both elastic and microplastic evolution. This leads to a heterogeneous internal stress distribution which, upon unloading, results in negative creep and complete residual-strain recovery. A detailed structural analysis in terms of local stress, atomic displacement, and SU(2) local bonding topology shows such mi- croscopic processes can result in large changes in local stress and are more likely to occur in geomet- rically frustrated regions characterized by higher free volume and softer elastic stiffness. The thermally- activated LSE activity also mediates structural relaxation, and in this way should be distinguished from stress-driven shear transformation activity which only rejuvenates glass structure. The frequency of LSE activity, and therefore the amount of micro-plasticity, is found to be related to the degree to which the glassy state is relaxed. These insights shed atomistic light onto the structural origins that may govern re- cent experimental observations of significant structural evolution in response to elastic loading protocols. KW - Molecular dynamics KW - Bulk metallic glasses KW - Plasticity KW - Residual strains PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-523782 DO - https://doi.org/10.1016/j.actamat.2021.116771 VL - 209 SP - 116771 PB - Elsevier Ltd. AN - OPUS4-52378 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stinville, J.C. A1 - Charpagne, M.A. A1 - Maaß, Robert A1 - Proudhon, H. A1 - Ludwig, W. A1 - Callahan, P.G. A1 - Wang, F. A1 - Beyerlein, I.J. A1 - Echlin, M.P. A1 - Pollock, T.M. T1 - Insights into Plastic Localization by Crystallographic Slip from Emerging Experimental and Numerical Approaches JF - Annual Review of Materials Research N2 - Advanced experimental and numerical approaches are being developed to capture the localization of plasticity at the nanometer scale as a function of the multiscale and heterogeneous microstructure present in metallic materials. These innovative approaches promise new avenues to understand microstructural effects on mechanical properties, accelerate alloy design, and enable more accurate mechanical property prediction. This article provides an overview of emerging approaches with a focus on the localization of plasticity by crystallographic slip. New insights into the mechanisms and mechanics of strain localization are addressed. The consequences of the localization of plasticity by deformation slip for mechanical properties of metallic materials are also detailed. KW - Slip localization KW - Metallic materials KW - Experimental and numerical techniques KW - Mechanical properties KW - Plasticity PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-578398 DO - https://doi.org/10.1146/annurev-matsci-080921-102621 SN - 1531-7331 VL - 53 SP - 275 EP - 317 AN - OPUS4-57839 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -