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

The lattice mismatch between the γ matrix and the γ′ precipitates in the AM1 superalloy was measured in situ during a creep experiment up to fracture (150 MPa, 1050 and 1080 °C) 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 °C, 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.