Paper Titles
The Importance of Residual Stresses in Microelectronic Products and Materials
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An X-Ray Diffraction Method to Determine Stress at Constant Penetration/Information Depth
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Mechanical Stress Gradients in Thin Films Analyzed Employing X-Ray Diffraction Measurements at Constant Penetration/Information Depths
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Sub-Surface Residual Stress Gradients: Advances in Laboratory XRD Methods
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Determination of Real Space Residual Stress Distributions σij(z) of Surface Treated Materials with Diffraction Methods Part I: Angle-Dispersive Approach
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Determination of Real Space Residual Stress Distributions σij(z) of Surface Treated Materials with Diffraction Methods Part II: Energy Dispersive Approach
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The Residual Stresses Generated by Deep Rolling and their Stability in Fatigue & Application to Deep-Rolled Crankshafts
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Stability of Residual Stresses of Deep Rolled Sintered Iron at Quasistatic and Cyclic Loading
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Residual Stress Stability in High Temperature Fatigued Mechanically Surface Treated Metallic Materials
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Mechanical Stress Gradients in Thin Films Analyzed Employing X-Ray Diffraction Measurements at Constant Penetration/Information Depths

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Abstract:

Stress gradients have been investigated employing a measurement strategy for diffraction measurements at constant penetration/information depths. Two examples have been considered: (i) sputter-deposited copper thin films on silicon wafers and (ii) γ’-Fe4N1-x layers on α-Fe substrates obtained by gaseous nitriding. In the Cu thin films rather low tensile stresses, increasing in magnitude with increasing penetration/information depth have been found. An evaluation of the measured lattice strains has been performed on the basis of the f(ψ) method, where the X-ray elastic constants (XEC’s) have been calculated as weighed averages of the corresponding Voigt and Reuss XEC’s and the weighing parameter has been taken as a fitting parameter. This evaluation reveals that the grain interaction changes with increasing penetration/information depth from near-Reuss type towards Neerfeld-Hill type. In the γ’-Fe4N1-x layers stress gradients occur due to surface relaxation near the surface and deeper in the layer due to a nitrogen concentration gradient which is built up during nitriding. First measurements in a laboratory diffractometer show the effect of surface relaxation on the stress-depth profile near the surface. As no single-crystal elastic constants are available for γ’-Fe4N1-x, the mechanical elastic constants have been employed in diffraction stress analysis. The results indicated that single-crystal elastic anisotropy occurs. From the measured data also a concentration – depth profile has been deduced.

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Periodical:

Materials Science Forum (Volumes 524-525)

Pages:

19-24

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.524-525.19

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Online since:

September 2006

Authors:

M. Wohlschlögel, W. Baumann, U. Welzel, Eric Jan Mittemeijer

Keywords:

Information Depth, Penetration Depth, Stress Gradient, X-Ray Diffraction Residual Stress Analysis

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© 2006 Trans Tech Publications Ltd. All Rights Reserved

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