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(a) Schematic view of the in situ cross-sectional X-ray nanodiffraction setup. A Cr 0.94 N microcantilever sample with dimensions 25 × 25 × 3 μm 3 (length × width × height), cut from a substrate-coating lamella, was scanned with an X-ray beam obtaining a cross-section of ∼250 nm. The microcantilever was loaded using a diamond wedge tip with a contact length of 10 μm, positioned at a distance of 23 μm from the pre-notch, and centered along the cantilever width. The 2D Debye-Scherrer diffraction patterns were recorded using an Eiger X M9 photon-counting detector. (b) Detail showing the geometry and deflection w ( t ) of the microcantilever under a static and/or cyclic load F ( t ), applied using the nanoindenter tip. (c) During static loading, the X-ray beam was scanned along the y-and z -axis in steps of 300 nm creating a 20 × 20 grid centered around the pre-notch position, whereas during (d) cyclic loading, three positions along the cantilever height ("top", "middle", "bottom"; located at the pre-notch position in y -direction) were repeatedly scanned for the duration of the loading experiment. (e) Representative intensity plot of the recorded Debye-Scherrer patterns. The

(a) Schematic view of the in situ cross-sectional X-ray nanodiffraction setup. A Cr 0.94 N microcantilever sample with dimensions 25 × 25 × 3 μm 3 (length × width × height), cut from a substrate-coating lamella, was scanned with an X-ray beam obtaining a cross-section of ∼250 nm. The microcantilever was loaded using a diamond wedge tip with a contact length of 10 μm, positioned at a distance of 23 μm from the pre-notch, and centered along the cantilever width. The 2D Debye-Scherrer diffraction patterns were recorded using an Eiger X M9 photon-counting detector. (b) Detail showing the geometry and deflection w ( t ) of the microcantilever under a static and/or cyclic load F ( t ), applied using the nanoindenter tip. (c) During static loading, the X-ray beam was scanned along the y-and z -axis in steps of 300 nm creating a 20 × 20 grid centered around the pre-notch position, whereas during (d) cyclic loading, three positions along the cantilever height ("top", "middle", "bottom"; located at the pre-notch position in y -direction) were repeatedly scanned for the duration of the loading experiment. (e) Representative intensity plot of the recorded Debye-Scherrer patterns. The

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Fatigue failure through sustained loading of ductile materials manifests in irreversible motion of dislocations, followed by crack initiation and growth. This contrasts with the mechanisms associated with brittle ceramics, such as nanostructured physical vapor deposited thin films, where inhibited dislocation mobility typically leads to interface-c...

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Context 1
... a double-side polished, cross-sectional substratecoating lamella with a thickness of ∼35 μm in beam direction was prepared by mechanical polishing of a Cr 0.94 N coated Si substrate. The lamella was subsequently secured to a sample holder, which allows for a precise horizontal alignment, guaranteeing a 90 ° contact angle of the coating surface to the nanoindenter tip, while avoiding any interference with diffracted beam paths during in situ cross-sectional X-ray nanodiffraction experiments (see Fig. 2 a). Using the above-mentioned FIB workstation, larger microcantilever specimens with a dimension of l × b × h = 25 × 25 × 3 μm 3 were ion-milled into the sample lamella. ...
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... scans covering a 20 × 20 mesh-grid in steps of 300 nm along the y-and z-axis were performed prior to the fatigue experiments to characterize the cross-sectional area of the cantilever around the pre-notch position (see Fig. 2 c). Thereby, three different static loading scenarios were investigated, with the cantilever incrementally loaded from ( i ) no force applied, to ( ii ) ∼35 % of K IC * (not shown here), and to ( iii ) ∼70 % of K IC * . ...
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... the abovementioned procedure and parameters, with the applied forces adjusted to F M = 0.65 × F C and F A = 0.15 × F C , respectively, resulting in the overall stress intensity oscillating between 50 and 80 % of K IC * . During these experiments, three distinct positions along the cantilever height, spaced 1 μm apart (top, middle, bottom; see Fig. 2 d), were repeatedly scanned for the duration of the loading procedure. This allowed for a detailed analysis of the phase and stress evolution within the cantilever material up to a total number of n = 5 × 10 6 load ...
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... were analyzed with respect to the phase evolution and the in-plane stress state σ , both for static as well as dynamic loading conditions. To evaluate the stress state of the cantilever cross-section σ ( y, z ) an integration of the recorded patterns was performed in direction of the azimuthal angle ψ in segments of 10 ° from ψ = 0 to 90 ° (see Fig. 2 e). Within the so obtained radial intensity distributions I( θ , ψ ) the positions of distinct diffraction peaks 2 θ (ψ ) hkl ( e.g. , (200)-peak for CrN), and thus also the orientation-dependent lattice spacing d (ψ ) hkl ...
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... more elaborate, detailed understanding of this observed material response from the aspect of intrinsic stress distributions and local phase formation was obtained by coupling the fatigue experiments with synchrotron X-ray nanodiffraction. Using this in situ synchrotron X-ray nanodiffraction setup, the phase evolution and stress state of larger micro-cantilever specimen was studied around the notch area in both the as-fabricated as well as under static (see Fig. 2 c) and dynamic loading conditions (see Fig. 2 d). These experiments aimed to correlate the observed fracture behavior and absence of fatigue induced damage with the intrinsic properties of the tested thin film materials. ...
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... more elaborate, detailed understanding of this observed material response from the aspect of intrinsic stress distributions and local phase formation was obtained by coupling the fatigue experiments with synchrotron X-ray nanodiffraction. Using this in situ synchrotron X-ray nanodiffraction setup, the phase evolution and stress state of larger micro-cantilever specimen was studied around the notch area in both the as-fabricated as well as under static (see Fig. 2 c) and dynamic loading conditions (see Fig. 2 d). These experiments aimed to correlate the observed fracture behavior and absence of fatigue induced damage with the intrinsic properties of the tested thin film materials. ...
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... representative stress distribution around the pre-notch position, calculated according to the procedure described in Figs. 2 e-g, is shown in Fig. 10 for a cantilever produced from the Cr 0.94 N coating. Fig. 10 a presents the in-plane stress distribution in the as-fabricated state ...
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... the actual stress distribution during the bending experiments, additional fatigue tests were conducted on these large cantilever specimens. Coupled with the cyclic loading, three distinct positions across the cantilever height were probed (see Fig. 2 d) using the in situ X-ray nanodiffraction setup to resolve the structural and stress state evolution. Fig. 11 a exemplarily depicts the results obtained for the Cr 0.94 N coating, showing the applied indenter force (left axis) as a function of the number of load cycles and an additional reference in terms of the critical stress intensity (right axis). ...
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... in all measurement positions. Altering the stress distribution, both towards tensile or compressive, would result in a distortion of the Debye-Scherrer ring pattern and a changed peak shape when fully integrating the diffracted intensity in azimuthal direction. Specifically verifying the stress distribution at n = 3 × 10 6 load cycles (see Fig. 12 a and b, red circles) assumes similar values as observed for static loading conditions in σ ( 0 , z ) of Figs. 10 c and d. An increased compressive stress of ∼ -1.5 GPa is calculated on the cantilever bottom, while the neutral axis and top surface roughly remain in their initial stress-free condition (blue diamonds, determined as cross-sectional average of ...