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Titel: Plasticity induced by nanoindentation in a CrCoNi medium-entropy alloy studied by accurate electron channeling contrast imaging revealing dislocation-low angle grain boundary interactions
VerfasserIn: Habiyaremye, Frederic
Guitton, Antoine
Schäfer, Florian
Scholz, Felicitas
Schneider, Mike
Frenzel, Jan
Laplanche, Guillaume
Maloufi, Nabila
Sprache: Englisch
Titel: Materials Science and Engineering: A
Bandnummer: 817
Verlag/Plattform: Elsevier
Erscheinungsjahr: 2021
DDC-Sachgruppe: 500 Naturwissenschaften
Dokumenttyp: Journalartikel / Zeitschriftenartikel
Abstract: In the present work, interactions of nanoindentation-induced dislocations (NIDs) with a low-angle grain boundary (LAGB) are investigated in a single-crystalline CrCoNi medium-entropy alloy (MEA). Microstructural evolutions before and after nanoindentation were examined using accurate electron channeling contrast imaging (A-ECCI). In the as-grown state, the alloy microstructure consists of subgrains separated by LAGBs. After nanoindentation on the (001) plane far away from LAGBs, the load-displacement curves exhibit the typical behavior of metals and alloys with a pop-in marking the elastic-plastic transition. This pop-in is related to the nucleation of NIDs that are observed to form pile-ups on {111} planes. In contrast, when indents are performed in the vicinity of a LAGB with a low misorientation angle of 0.24° and consisting of dislocations spaced ~60 nm apart, different micromechanical responses and deformation mechanisms are observed depending on the distance between the LAGB and the nanoindenter tip. When the distance between the LAGB and the nanoindenter tip is larger than four times the size of the indent (corresponding ratio: R > 4), the LAGB does not affect the micromechanical response nor interact with NIDs. In contrast, when the indenter comes in direct or indirect contact with the LAGB (R < 1), the load-displacement curve deviates at low loads from the elastic stage, and pop-ins are not observed. In this case, the continuous deformation is accommodated by the movement of the pre-existing LAGB dislocations. For intermediate cases with 1 < R < 4, the load of the initial pop-in is dependent on the local defect density. In this latter case, the pile-ups of NIDs directly impinge on the LAGB. Microstructural analyses reveal that the LAGB accommodates plasticity by blocking the NIDs, activating a dislocation nucleation site in the adjacent subgrain/emission of dislocation from the LAGB, and inducing slight motions of its constituent dislocations.
DOI der Erstveröffentlichung: 10.1016/j.msea.2021.141364
URL der Erstveröffentlichung: https://www.sciencedirect.com/science/article/abs/pii/S092150932100633X
Link zu diesem Datensatz: urn:nbn:de:bsz:291--ds-401193
hdl:20.500.11880/36110
http://dx.doi.org/10.22028/D291-40119
ISSN: 0921-5093
Datum des Eintrags: 14-Jul-2023
Fakultät: NT - Naturwissenschaftlich- Technische Fakultät
Fachrichtung: NT - Materialwissenschaft und Werkstofftechnik
Professur: NT - Prof. Dr. Christian Motz
Sammlung:SciDok - Der Wissenschaftsserver der Universität des Saarlandes

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