Authors: Shenyan Huang Donald W Brown Bjørn Clausen Zhenke Teng Yanfei Gao Peter K Liaw
Publish Date: 2011/11/15
Volume: 43, Issue: 5, Pages: 1497-1508
Abstract
Precipitate strengthening effects toward the improved creep behavior have been investigated in a ferritic superalloy with B2type NiFeAl precipitates In situ neutron diffraction has been employed to study the evolution of the average phase strains hkl planespecific lattice strains interphase lattice misfit and grainorientation texture during creep deformation of the ferritic superalloy at 973 K 700 °C The creep mechanisms and particledislocation interactions have been studied from the macroscopic creep behavior At a low stress level of 107 MPa the dislocationclimbcontrolled powerlaw creep is dominant in the matrix phase and the load partition between the matrix and the precipitate phases remains constant However intergranular stresses develop progressively during the primary creep regime with the load transferred to 200 and 310 oriented grains along the axial loading direction At a high stress level of 150 MPa deformation is governed by the thermally activated dislocation glide powerlaw breakdown accompanied by the accelerated texture evolution Furthermore an increase in stress level also leads to load transfer from the plastically deformed matrix to the elastically deformed precipitates in the axial direction along with an increase in the lattice misfit between the matrix and the precipitate phasesThis work was supported financially by the US Department of Energy DOE Office of Fossil Energy under Grants DEFG2606NT42732 and DE09NT0008089 The work has benefitted from the use of the Lujan Neutron Scattering Center at LANSCE which is funded by the Office of Basic Energy Sciences DOE Los Alamos National Laboratory is operated by the Los Alamos National Security LLC under the DOE Contract DEAC5206NA25396 The authors would like to thank Prof Morris Fine Prof Gautam Ghosh at Northwestern University Prof Mark Asta at University of California Berkeley and Prof Chain T Liu at the City University of Hong Kong for their collaborations in this program Note that the TEM work was published in Ref 4 and was conducted by Prof Gautam Ghosh YF Gao acknowledges support from the Center for Defect Physics an Energy Frontier Research Center funded by the US Department of Energy Office of Science
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