Paper Title:
Diffraction Profile, Strain Distribution and Dislocation Densities during Stage II Creep of a Superalloy
  Abstract

One of the major ingredients of modelling the mechanical behaviour of superalloys is the knowledge of dislocation densities and strain distribution. Both can be measured using post mortem BF TEM and CBED, but such methods do not allow following their variations during a test. The aim of the present work is to investigate the usefulness of in situ X-Ray Three Crystal Diffractometry (TCD) to measure the density and distribution of dislocations within a rafted superalloy, i.e. during stage II of high temperature creep. As the instrument contribution is very low, the two-peaked experimental profiles are representative of the lattice parameter distribution within the material. The profiles were measured within bulk specimens at the BW5 high energy beamline Hasylab (DESY), during high temperature (1050°C to 1180°C) tests under loads between 0 MPa and 300 MPa. The peak shapes were observed to change with varying experimental conditions. The peak width follows different patterns under low and high stress, i.e. with low and high strain rates. The distribution of elastic strains was calculated by assuming two main contributions: dislocation segments trapped at the γ/γ’ interfaces in a more or less regular network, and dislocations moving within the γ’ rafts. A comparison between experimental and simulated peaks shows that several features of their behaviour can be explained: the absolute magnitude of the peak width, the observed decrease of the peak width under low loads with increasing interfacial dislocation densities. The larger increase in the width of the γ’ peak under high load (and strain rate) may be attributed to a dislocation density within the 1013 m-2 range within the rafts. The present results are presently being cross-checked by post mortem TEM observations.

  Info
Periodical
Edited by
M. Heilmaier
Pages
37-41
DOI
10.4028/www.scientific.net/AMR.278.37
Citation
L. Dirand, A. Jacques, J. P. Chateau, T. Schenk, O. Ferry, P. Bastie, "Diffraction Profile, Strain Distribution and Dislocation Densities during Stage II Creep of a Superalloy", Advanced Materials Research, Vol. 278, pp. 37-41, 2011
Online since
July 2011
Export
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: Bo Jakobsen, Ulrich Lienert, Jonathan Almer, Wolfgang Pantleon, Henning Friis Poulsen
Abstract:The synchrotron based X-ray diffraction method “High angular resolution 3DXRD” is briefly introduced. The technique enables the...
613
Authors: Eiichi Sato, Tetsuya Matsunaga
Abstract:Hexagonal close-packed metals and alloys show significant creep behavior with extremely low activation energies at and below ambient...
299
  | Authors: Florence Pettinari-Sturmel, Joël Douin, Didier Locq, Pierre Caron, Armand Coujou
Abstract:The mechanical behavior of the polycrystalline NR3 Ni-based superalloy has been investigated at the microscopic scale. The elementary...
13
Authors: Su Gui Tian, Ben Jiang Qian, Fu Shun Liang, An An Li, Xing Fu Yu
Abstract:By the measurement of creep curves and microstructure observation, an investigation has been made into the creep behaviors and microstructure...
276
Authors: Hong Fu Xiang, Jing Hai Tao, Ji Heng Wang, Hui Li, An Lun Dai
Chapter 2: Engineering Materials Research
Abstract:A beta phase containing titanium aluminum compound was prepared. Isothermal Fatigue(IF) were subjected at 650 °C at three strain rates, such...
314