Slip band characteristics in the presence of grain boundaries in nickel-based superalloy

Slip band characteristics in the presence of grain boundaries in nickel-based superalloy

Slip band characteristics in the presence of grain boundaries in nickel-based superalloy 150 150 UKAEA Opendata
UKAEA-CCFE-PR(20)02

Slip band characteristics in the presence of grain boundaries in nickel-based superalloy

Shear strain profiles along slip bands in a modified Rolls-Royce nickel superalloy (RR1000) were analyzed for tensile sample deformed by 2%. The strain increased with distance away from a grain boundary (GB), with maximum shear strain towards the center of the grain, indicating that dislocation nucleation generally occurred in the grain interior. The strain gradients in the neighborhood of the GBs were quantified and showed rotation about the active slip system line direction. The dislocation spacing and pileup stresses were inferred. The dislocation spacing closely follows an Eshelby analytical solution for a single ended pileup of dislocations under an applied stress. The distribution of pileup stress values for GBs of a given misorientation angle between both grains follows a log-normal distribution, with no correlation between the pileup stress and the GB misorientation angle. Furthermore, there is no observed correlation between various transmissivity factors and slip band pileup stress. Hence it appears that the obstacle strength of any of the observed GBs is adequate to cause the dislocation pileups present in the slip bands. Slip band transmission is influenced by transmissivity factors with particular interest in the Luster and Morris m’-factor.  Transmission occurs at higher m’ values, except at twin boundaries which show transmission peaking at m’ values of 0.78. Observation of strain profiles of transmitted bands show dislocation nucleation in one grain, both grains, and at the grain boundary.

Collection:
Journals
Journal:
Acta Materialia
Publisher:
Elsevier
Published date:
05/06/2020