Ledges and grooves at γ/γ′ interfaces of single crystal superalloys

0449613 - ÚFM 2016 RIV GB eng J - Článek v odborném periodiku
Parsa, A. B. - Wollgramm, P. - Buck, H. - Kostka, A. - Somsen, C. - Dlouhý, Antonín - Eggeler, G.
Ledges and grooves at γ/γ′ interfaces of single crystal superalloys.
Acta Materialia. Roč. 90, MAY (2015), s. 105-117. ISSN 1359-6454. E-ISSN 1873-2453
Grant CEP: GA ČR(CZ) GA14-22834S
Institucionální podpora: RVO:68081723
Klíčová slova: Ni-base single crystal superalloys * γ/γ′ interfaces * Interface dislocations * Rafting * Grooves
Kód oboru RIV: JG - Hutnictví, kovové materiály
Impakt faktor: 5.058, rok: 2015

In the present work we study the formation of grooves and ledges (typical size: <100 nm) at γ/γ′ interfaces of single crystal Ni-base superalloys. We highlight previous work which documents the presence of such interface irregularities and shows that their number and size increases during high temperature exposure and creep. We use diffraction contrast stereo transmission electron microscopy (TEM) to provide new evidence for the presence of ledges and grooves near dislocations at γ/γ′ interfaces after heat treatment and creep. We present a 2D model of the interfacial region which shows how dislocation stress fields alter local chemical potentials and drive diffusional fluxes which result in the formation of a groove. The results of the numerical study yield realistic groove sizes in relevant time scales. The results obtained in the present study suggest that the formation of grooves and ledges represents an elementary process which needs to be considered when rationalizing the kinetics of rafting, the directional coarsening of the γ′ phase.
Trvalý link: http://hdl.handle.net/11104/0251141