Diffraction analysis of strongly inhomogeneous residual stress depth distributions by modification of the stress scanning method. II. Experimental implementation

Abstract

The modified stress scanning method [http://scripts.iucr.org/cgi-bin/paper?to5114] is experimentally implemented for the analysis of near‐surface residual stress depth distributions that are strongly inhomogeneous. The suggested procedure is validated by analyzing the very steep in‐plane residual stress depth profile of a shot‐peened Al2O3 ceramic specimen and comparing the results with those that were obtained by well established X‐ray diffraction‐based gradient methods. In addition, the evaluation formalism is adapted to the depth‐dependent determination of the residual stresses inside of multilayer thin‐film systems. The applicability for this purpose is demonstrated by investigating the residual stress depth distribution within the individual sublayers of a multilayered coating that consists of alternating Al2O3 and TiCN thin films. In this connection, the specific diffraction geometry that was used for the implementation of the stress scanning method at the energy‐dispersive materials science beamline EDDI@BESSYII is presented, and experimental issues as well as limitations of the method are discussed.

Diffraction analysis of strongly inhomogeneous residual stress depth distributions by modification of the stress scanning method. I. Theoretical concept

“…The modified data evaluation procedure, which was proven by simulations to be suitable for the detection of strongly inhomogeneous near-surface residual stress depth distributions inside of bulk samples in the present paper, will be shown to deploy its full strengths in the case of investigating alternately stacked multilayer systems in the second part of this series (Meixner et al, 2015). While near-surface residual stress depth profiling within bulk materials may be performed with comparatively little effort by means of gradient methods based on the Laplace approach, the introduced concept offers the possibility to nondestructively access the residual stress depth distribution inside the individual sublayers of alter-nately stacked multilayer coatings, even in the case of deeply buried sublayers.…”

“…Owing to this effect, the reliable determination of the residual stress gradient jj ðzÞ requires the quantification of the sample tilt Á and its consideration in the evaluation by means of the geometrical weighting factor g xy ðz; ¼0 ;z Ã Þ in equation 11. A possible approach for the determination of Á is presented in the second part of this paper (Meixner et al, 2015).…”

Nondestructive separation of residual stress and composition gradients in thin films by angle- and energy-dispersive X-ray diffraction. II. Experimental validation

“…With usable photon energies between about 8 and 120 keV provided by a 7 T multipole wiggler, this beamline is primarily dedicated to the analysis of near-surface material zones of up to several hundred micrometres, or even to study samples in transmission geometry (Genzel et al, 2011;García-Moreno et al, 2013). However, in the past decade it was demonstrated that high-energy white-beam diffraction can also be applied to the study of residual stress gradients in thin films and multilayers (Meixner et al, 2015). The experimental parameters applied in the ED measurements are listed in Table 2.…”