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The brittle-to-ductile transition in cold-rolled tungsten sheets: the rate-limiting mechanism of plasticity controlling the BDT in ultrafine-grained tungsten

Bonnekoh, Carsten; Reiser, Jens; Hartmaier, Alexander; Bonk, Simon; Hoffmann, Andreas; Rieth, Michael

Conventionally produced tungsten (W) sheets are brittle at room temperature. In contrast to that, severe deformation by cold rolling transforms W into a material exhibiting room-temperature ductility with a brittle-to-ductile transition (BDT) temperature far below room temperature. For such ultrafine-grained (UFG) and dislocation-rich materials, the mechanism controlling the BDT is still the subject of ongoing debates. In order to identify the mechanism controlling the BDT in room-temperature ductile W sheets with UFG microstructure, we conducted campaigns of fracture toughness tests accompanied by a thermodynamic analysis deducing Arrhenius BDT activation energies. Here, we show that plastic deformation induced by rolling reduces the BDT temperature and also the BDT activation energy. A comparison of BDT activation energies with the trend of Gibbs energy of kink-pair formation revealed a strong correlation between both quantities. This demonstrates that out of the three basic processes, nucleation, glide, and annihilation, crack tip plasticity in UFG W is still controlled by the glide of dislocations. The glide is dictated by the mobility of the screw segments and therefore by the underlying process of kink-pair formation. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000120012
Veröffentlicht am 05.06.2020
DOI: 10.1007/s10853-020-04801-5
Zitationen: 6
Zitationen: 6
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Angewandte Materialien - Angewandte Werkstoffphysik (IAM-AWP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 0022-2461, 1573-4803
KITopen-ID: 1000120012
HGF-Programm 31.03.09 (POF III, LK 01) Strukturmaterial f. Blanket und Divertor
Erschienen in Journal of materials science
Verlag Springer
Band 55
Seiten 12314–12337
Vorab online veröffentlicht am 19.05.2020
Nachgewiesen in Dimensions
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