The evolution of the lattice parameter mismatch of nickel based superalloy:: an in situ study during creep deformation

The lattice mismatch between the,, matrix and the gamma' precipitates in the AM I superalloy was measured in situ during a creep experiment up to fracture (150 MPa, 1050 and 1080 degreesC) by high energy XRD at the ID 15 beamline of the ESRF. The results are coherent with experiments done post mortem on specimens just annealed, and a specimen strained at 1050 degreesC, 150 MPa up to 1.03%. From the evolution of the mismatch. it is proposed that the elastic interfacial energy varies strongly during a creep test, and might put a limit on the high temperature ductility of superalloys. (C) 2001 Elsevier Science B.V. All rights reserved.