scholarly journals Stress-Dependent Elasticity of TiAlN Coatings

Coatings ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 24 ◽  
Author(s):  
Marcus Hans ◽  
Lena Patterer ◽  
Denis Music ◽  
Damian M. Holzapfel ◽  
Simon Evertz ◽  
...  
Keyword(s):  
Residual Stress ◽  
Elastic Modulus ◽  
Stress State ◽  
Effective Medium Theory ◽  
Plasma Exposure ◽  
X Ray ◽  
Residual Stress State ◽  
Scanning Transmission ◽  
The Matrix ◽  
Stress Dependent

We investigate the effect of continuous vs. periodically interrupted plasma exposure during cathodic arc evaporation on the elastic modulus as well as the residual stress state of metastable cubic TiAlN coatings. Nanoindentation reveals that the elastic modulus of TiAlN grown at floating potential with continuous plasma exposure is 7%–11% larger than for coatings grown with periodically interrupted plasma exposure due to substrate rotation. In combination with X-ray stress analysis, it is evident that the elastic modulus is governed by the residual stress state. The experimental dependence of the elastic modulus on the stress state is in excellent agreement with ab initio predictions. The macroparticle surface coverage exhibits a strong angular dependence as both density and size of incorporated macroparticles are significantly lower during continuous plasma exposure. Scanning transmission electron microscopy in combination with energy dispersive X-ray spectroscopy reveals the formation of underdense boundary regions between the matrix and TiN-rich macroparticles. The estimated porosity is on the order of 1% and a porosity-induced elastic modulus reduction of 5%–9% may be expected based on effective medium theory. It appears reasonable to assume that these underdense boundary regions enable stress relaxation causing the experimentally determined reduction in elastic modulus as the population of macroparticles is increased.

Residual Stress Measurements in Continuous Fiber Titanium Matrix Composites

1992 ◽  
Vol 36 ◽  
pp. 481-488 ◽  
Author(s):  
M. R. James ◽  
M. A. Bourke ◽  
J. A. Goldstone ◽  
A. C. Lawson
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Thin Sheet ◽  
Matrix Composites ◽  
X Ray ◽  
Residual Stress State ◽  
Longitudinal Residual Stress ◽  
The Matrix ◽  
Reinforcement Fiber ◽  
Residual Strains

AbstractMetal matrix composites develop residual strains after consolidation due to the thermal expansion mismatch between the reinforcement fiber and the matrix. X-ray and neutron diffraction measured values for the longitudinal residual stress in the matrix of three titanium MMCs are reported. For thick composites (> 6 plies) the surface stress measured by x-ray diffraction matches that determined by neutron diffraction and therefore represents the stress in the bulk region consisting of the fibers and matrix. For thin sheet composites, the surface values are lower than in the interior and increase as the outer rows of fibers are approached. While a rationale for this behavior has yet to be developed, accounting for composite thickness is important when using x-ray measured values to validate analytic and finite element calculations of the residual stress state.

X-ray diffraction analysis of the residual stress state in PVD TiN/CrN multilayer coatings deposited on tool steel

2005 ◽  
Vol 200 (1-4) ◽  
pp. 165-169 ◽  
Author(s):  
C. Mendibide ◽  
P. Steyer ◽  
C. Esnouf ◽  
P. Goudeau ◽  
D. Thiaudière ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Diffraction Analysis ◽  
Tool Steel ◽  
Multilayer Coatings ◽  
X Ray Diffraction ◽  
X Ray ◽  
Residual Stress State

Pattern decomposition for residual stress analysis: a generalization taking into consideration elastic anisotropy and extension to higher-symmetry Laue classes

2017 ◽  
Vol 50 (4) ◽  
pp. 1011-1020 ◽  
Author(s):  
Peter Schoderböck ◽  
Peter Leibenguth ◽  
Michael Tkadletz
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Hard Coatings ◽  
Titanium Carbonitride ◽  
X Ray ◽  
Residual Stress State ◽  
Pattern Decomposition ◽  
Decomposition Procedure

The residual stress state of ion-conducting layers (yttria stabilized zirconia) and protective hard coatings (α-aluminium oxide, titanium carbonitride) was investigated using X-ray diffraction techniques. Its evaluation within the tetragonal, trigonal and cubic phases present was performed by a whole powder pattern decomposition procedure according to Pawley. Going beyond previous work, the applied refinements directly include the influence of elastic anisotropy on the residual stress results. Starting from the single-crystal elastic coefficients, the X-ray elastic constants according to the Voigt and Reuss models were calculated. Finally, the Neerfeld–Hill model as a generalization was implemented to introduce thehkl-specific X-ray elastic constants for calculating the residual stress magnitude within the least-squares minimization routine. It was possible to resolve the residual stress state in stacked layers of different chemical and phase composition and to reproduce the results obtained by the classical χ- and ω-inclination sin2Ψ techniques.

Mechanical Property Scatter in CFCCs

1998 ◽  
Author(s):  
Marc Steen ◽  
Constantina Filiou
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Mechanical Response ◽  
Ceramic Matrix Composites ◽  
Strength Properties ◽  
Matrix Cracking ◽  
Control Mode ◽  
Residual Stress State ◽  
The Matrix

The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of 2D reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc.. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented.

Mechanical Property Scatter in CFCCs

1999 ◽  
Vol 122 (1) ◽  
pp. 69-72 ◽  
Author(s):  
M. Steen ◽  
C. Filiou
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Mechanical Response ◽  
Ceramic Matrix Composites ◽  
Strength Properties ◽  
Matrix Cracking ◽  
Control Mode ◽  
Residual Stress State ◽  
The Matrix

The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of two-dimensional reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented. [S0742-4795(00)01101-7]

Hydrogen Interaction with Residual Stresses in Steel Studied by Synchrotron X-Ray Diffraction

2013 ◽  
Vol 772 ◽  
pp. 91-95 ◽  
Author(s):  
Eitan Dabah ◽  
Thomas Kannengiesser ◽  
Dan Eliezer ◽  
Thomas Boellinghaus
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
High Energy ◽  
Steel Sample ◽  
Stainless Steel Sample ◽  
X Ray Diffraction ◽  
High Hydrogen ◽  
X Ray ◽  
Residual Stress State

The residual stress state in a material has an important role in the mechanism of cracking, induced or assisted by hydrogen. In this contribution, the beamline EDDI in BESSY II instrument in Berlin was used in order to investigate the influence of hydrogen upon the residual stresses state existing in a Supermartensitic stainless steel sample. The method used for investigating the residual stresses is the “sinus square ψ” method. This method involves the usage of high energy X-ray diffraction in order to measure the residual stress state and magnitude. It was found that hydrogen presence has a significant influence upon the magnitude of the residual stresses, as its value decreases with high hydrogen content. This effect is reversible, as hydrogen desorbs from the sample the residual stress magnitude gains its initial value before hydrogen charging.

scholarly journals Neutron and X-Ray Diffraction Residual Stress Measurements in Aluminium Alloys MIG Welded T-Joints after Friction Stir Processing

2014 ◽  
Vol 996 ◽  
pp. 439-444 ◽  
Author(s):  
João P. Nobre ◽  
António Castanhola Batista ◽  
Joana R. Kornmeier ◽  
José D. Costa ◽  
Altino Loureiro ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress State ◽  
Friction Stir Processing ◽  
Aluminium Alloys ◽  
X Ray Diffraction ◽  
T Joints ◽  
X Ray ◽  
Friction Stir ◽  
Residual Stress State

Friction Stir Processing (FSP) is a relatively new post-processing technique. Fatigue strength of MIG fillet welds of aluminium alloys can be substantially improved using FSP. Beyond other properties intrinsically tied to fatigue life, especially attention should be paid to the effect of the final residual stress state. In this study the residual stress distribution in T-joints of two aluminium alloys was determined by Neutron and X-ray diffraction. FSP effect on the residual stress state and fatigue life was analysed.

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