On the nucleation of planar faults during low temperature and high stress creep of single crystal Ni-base superalloys

0497067 - ÚFM 2019 RIV GB eng J - Článek v odborném periodiku
WU, X. - Dlouhý, Antonín - Eggeler, Y. M. - Spiecker, E. - Kostka, A. - Somsen, C. - Eggeler, G.
On the nucleation of planar faults during low temperature and high stress creep of single crystal Ni-base superalloys.
Acta Materialia. Roč. 144, FEB (2018), s. 642-655. ISSN 1359-6454. E-ISSN 1873-2453
Grant CEP: GA ČR(CZ) GA14-22834S
Institucionální podpora: RVO:68081723
Klíčová slova: Ni-base superalloy single crystals * Low temperature and high stress primary creep * Nucleation of planar faults * Gamma channel dislocations
Obor OECD: Materials engineering
Impakt faktor: 7.293, rok: 2018

The present work studies the nucleation of planar faults in the early stages of low temperature (750 °C) and high stress (800 MPa) creep of a Ni-base single crystal superalloy (SX). Two families of 60° dislocations with different Burgers vectors were detected in the transmission electron microscope (TEM). These can react and form a planar fault in the γ′ phase. A 2D discrete dislocation model helps to rationalize a sequence of events which lead to the nucleation of a planar fault. First, one 60° channel dislocation approaches another 60° interface dislocation with a different Burgers vector. At a distance of 5 nm, it splits up into two Shockley partials. The interface dislocation is pushed into the γ′-phase where it creates a small antiphase boundary. It can only move on when the leading Shockley partial joins it and creates an overall 1/3112 superdislocation. This process is fast and therefore is difficult to observe. The results obtained in the present work contribute to a better understanding of the processes which govern the early stages of low temperature and high stress primary creep of SX.
Trvalý link: http://hdl.handle.net/11104/0289680