Full elastic strain tensor determination at the phase scale in a powder metallurgy nickel-based superalloy using X-ray Laue microdiffraction

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. Laue microdiffraction is used to determine the full elastic strain tensor of the and 0 phases in grains of a nickel-based superalloy with a coarse-grained microstructure. A 'rainbow' filter and an energy dispersive point detector are employed to measure the energy of Bragg reflections. For the two techniques, an uncertainty of AE2.5 Â 10 À3 Å is obtained for the undetermined crystal lattice parameter. Our measurements show that the filter method provides better confidence, energy resolution, accuracy and acquisition time. The sensitivity of each method with respect to the -0 lattice mismatch is demonstrated with measurements in samples with average precipitate sizes of 200 and 2000 nm. For the 200 nm precipitate size, the lattice mismatch is less than 2 Â 10 À3 Å and the dilatational strains are close to AE1.5 Â 10 À3 depending on the considered phase. For the 2000 nm precipitate size, the lattice mismatch is close to 8 Â 10 À3 Å and almost no elastic strain occurs in the microstructure.

Local strain redistribution in a coarse-grained nickel-based superalloy subjected to shot-peening, fatigue or thermal exposure investigated using synchrotron X-ray Laue microdiffraction

“…The fact that it was difficult to measure the energy of a fundamental and a superstructure reflections at each sample position was also an important limitation of the method. The "Rainbow" technique [39] would be a good alternative because energy resolutions of 1 eV may be obtained for the two types of reflection at every sample position [45]. Concerning, a better characterization of the hardened layer, a depth resolution is required in order to have workable outcomes.…”