|A neutron diffraction study of lattice distortion, mismatch and misorientation in a single-crystal superalloy after different heat treatments|
|E. D. Wu; G. A. Sun; B. Chen; T. Pining; D. J. Hughes; S. C. Wang; J. Zhang
|Source Publication||Acta Materialia
|Abstract||Two-dimensional neutron diffraction measurements of superlattice and fundamental lattice reflections from a single-crystal superalloy confirm the existence of angular distortion and shear stress in the gamma' phase, and reveal its correlation with the morphology and deformation of the gamma' phase during heat treatment. The tetragonal distortions with c/a > 1 are developed and retained during subsequent heat treatments, whereas the angular distortions are enhanced for the gamma' phase during the aging treatments. The evolution of the lattice mismatch and anisotropy during the subsequent heat treatments are consistent with the transformation of certain macroscopic anisotropic compositional and stress distributions in the as-cast sample to the microscopic level at the gamma/gamma'-interface upon reprecipitation and the growth of the gamma' from the supersaturated gamma-matrix. The high negative gamma/gamma lattice mismatch of the alloy is consistent with the high levels of refractory elements, in particular Cr, in the alloy. Comparison between superlattice and fundamental lattice reflections is revealing. Firstly, the existence of lattice misorientation at the gamma/gamma'-interface and the discrete misorientations from the splitting of coherently aligned aggregates of gamma'-precipitates on the smoothly distributed gamma-matrix is shown. Secondly, the measured lattice misorientation correlates with the spacing of dislocations at the gamma/gamma'-interface and evidenced by the transmission electron microscopy observation. Furthermore, it indicates the anisotropic distribution of dendrites along crystal growth axis and the presence of small misoriented higher-order dendrite arms in variously heat-treated samples. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.|
; wang, sucheng
; zhang, jian] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china. [sun, guangai
; chen, bo] caep, inst nucl phys & chem, mianyang 621900, peoples r china. [pining, thilo] inst max von laue paul langevin, f-38042 grenoble, france. [hughes, darren j.] univ warwick, wmg, coventry cv4 7al, w midlands, england.
; wu, ed (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china.
E. D. Wu,G. A. Sun,B. Chen,et al. A neutron diffraction study of lattice distortion, mismatch and misorientation in a single-crystal superalloy after different heat treatments[J]. Acta Materialia,2013,61(7):2308-2319.
E. D. Wu.,G. A. Sun.,B. Chen.,T. Pining.,D. J. Hughes.,...&J. Zhang.(2013).A neutron diffraction study of lattice distortion, mismatch and misorientation in a single-crystal superalloy after different heat treatments.Acta Materialia,61(7),2308-2319.
E. D. Wu,et al."A neutron diffraction study of lattice distortion, mismatch and misorientation in a single-crystal superalloy after different heat treatments".Acta Materialia 61.7(2013):2308-2319.
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