Depth-dependent defect and residual stress distribution in magnetron sputtered MoN:Cu nanocomposite films by x-ray microdiffraction

2006 ◽  
Vol 977 ◽  
Author(s):  
Gang Chen ◽  
Dileep Singh ◽  
Osman Eryilmaz ◽  
Ali Erdemir ◽  
Jules Routbort ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
High Hardness ◽  
Residual Stress Distribution ◽  
Nanocomposite Films ◽  
Structure Property ◽  
Nanocrystalline Films ◽  
Low Friction ◽  
X Ray ◽  
Property Relations

AbstractWe have developed a synchrotron-based x-ray microdiffraction technique for measuring depth-resolved residual stress distribution in nanocrystalline films with submicron resolution [1]. In this study, we further refined this technique and applied it to low-friction and high-hardness Cu-doped MoN films. These magnetron sputtered nanocomposites films consist of MoN, Mo2N, and Cu phases, whose ratio depends on Cu concentration. By using the microdiffraction technique, we discovered that both the deviatoric and the hydrostatic components of the residual stresses depend on the film depth (Fig.1). The former indicates depth-dependent distribution of biaxial stresses, while the latter implies depth-dependent defect distribution, which also depends on Cu concentration. Thermal annealing of the nanocomposite film partially relives the stress, significantly reduces the lattice spacing, and eliminates the defect gradients. These results suggest that interstitial N may play an important role in the lattice expansion and the defect gradients formed during the non-equilibrium sputtering process. Our study provides fresh insights into understanding the structure-property relations in the magnetron sputtered MoN:Cu nanocomposites films.

Residual Stress and Microstructure in the Rail/Wheel Contact Zone of a Worn Railway Wheel

2006 ◽  
Vol 524-525 ◽  
pp. 911-916 ◽  
Author(s):  
Eric Wild ◽  
Walter Reimers
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
High Hardness ◽  
Residual Stress Distribution ◽  
X Ray Diffraction ◽  
Wheel Surface ◽  
X Ray ◽  
Microstructural Alterations ◽  
Hardness Values ◽  
Compressive Residual Stresses

The rail/ wheel contact comprises interactions of thermal and mechanical loadings which lead to microstructural changes in the wheel. These were investigated on a wheel from a regional train using metallographic examinations, X-ray diffraction for phase and residual stress analyses. The results show that the microstructural alterations, the carbon content and the residual stress distribution depend on the loading profile of the wheel. The formation of two different martensites (tetragonal and cubic martensite) on a wheel surface could be detected at different positions. The martensites are characterized by high hardness values, increased carbon contents in the lattice and an increased level of compressive residual stresses. Detailed structural analyses of the martensites which were formed under locally different loading and time conditions gave evidence for different structural evolutions.

Measurement of Residual Stress Distribution of Ground Silicon Nitride by Glancing Incidence X-ray Diffraction Technique

1995 ◽  
Vol 39 ◽  
pp. 331-338
Author(s):  
Yoshihisa Sakaida ◽  
Keisuke Tanaka ◽  
Shintaro Harada
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Stress Distribution ◽  
Stress Measurement ◽  
Scintillation Counter ◽  
Ground Surface ◽  
Residual Stress Distribution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Very High

A new method of X-ray stress measurement was proposed to estimate non-destructively the steep residual stress distribution in the surface layer of ground Si3N4. We assumed an exponential decrement of the residual stress near the ground surface, and derived a formula for the lattice strain as a function of sin2Ψ. In the experiments, the diffraction angles were measured on the ground surface for a widest possible range of sin2ѱ using an Ω-goniometer. In order to measure the diffraction angle at very high sin η values, a scintillation counter was located on the -η side and an incident X-ray beam impinged on the ground surface with a very low angle from the +η side using the glancing incidence X-ray diffraction technique. A strong non-linearity was found in the 20-sin2ѱ diagrams especially at very high ѱ -angles. From the analysis of non-linearity, the stress distribution in the surface layer was determined. Tine residual stress took the maximum compression of 2 GPa at a depth of about 0.5 μm from the surface, and then diminished to zero at about 25 μm in depth. In the close vicinity of the ground surface, the compressive residual stress was relieved because of both the surface roughness and microcracking induced during the grinding process.

On Axisymmetric Residual Stresses in Tubes With Longitudinally Nonuniform Stress Distribution

1993 ◽  
Vol 60 (2) ◽  
pp. 300-309 ◽  
Author(s):  
T. Nishimura
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Diffraction Method ◽  
Residual Stress Distribution ◽  
New Method ◽  
Element Analysis ◽  
Simple Modification ◽  
X Ray

New equations for calculating residual stress distribution are derived from the theory of elasticity for tubes. The initial distribution of the stresses including the shearing stress is computed from longitudinal distributions of residual stresses measured by the X-ray methods at the surface after removal of successive concentric layers of material. For example, the residual stresses of a steel tube quenched in water were measured by the X-ray diffraction method. The new method was also applied to a short tube with hypothetical residual stress distribution. An alternative finite element analysis was made for a verification. The residual stresses computed by finite element modeling agreed well with the hypothetical residual stresses measured. This shows that good results can be expected from the new method. The equations can also be used for bars by simple modification.

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