H. Biermann et al., Determination of local strains in a monocrystalline turbine blade by microbeam X-ray diffraction with synchrotron radiation, ACT MATER, 48(9), 2000, pp. 2221-2230
X-ray peak profiles of the types {400} and {300} of monocrystalline nickel-
based superalloy turbine blades were measured with a new microbeam synchrot
ron radiation X-ray diffraction technique. Under the coating of a turbine b
lade in the virgin state, a plastically deformed layer was found which is r
esponsible for anomalous rafting. In a turbine blade subjected to an "accel
erated mission test", the phases gamma and gamma' were found to be under el
astic distortions arising from the superposition of counteracting internal
stresses. It is concluded that the investigated section was under tensile c
reep load during service. In the regions near the surfaces, the lattice par
ameters of both gamma and gamma' increase. The reason for this increase is
the diffusion of Al from the NiAl coating into the bulk of the blade. Final
ly, the differences between the peak profiles measured with the microfocus
technique and with a conventional diffractometer are discussed. (C) 2000 Ac
ta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved
.