In-Situ Analysis of Microstress and Texture Development during Tensile Deformation of MMCs at Room Temperature and at Elevated Temperatures Using Synchrotron Radiation

Pyzalla, A.; Reetz, Björn; Wegener, J.; Jacques, Alain; Ferry, Olivier; Feiereisen, J.P.; Buslaps, T.

doi:10.4028/www.scientific.net/msf.404-407.535

Cited by 2 publications

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“…Characterization of the local stress and strain within bulk materials has been performed by numerous groups, using both energy-dispersive settings and monochromatic setups, e.g. [57,65,66,67,68,69,70,71,72,73,74].…”

Section: Hard X-ray Work Using Synchrotron Sourcesmentioning

confidence: 99%

Methods for Mesoscale Structural Characterization

Poulsen

2004

Springer Tracts in Modern Physics

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As a motivation for introducing the 3DXRD method, this chapter contains a survey of the experimental methods conventionally used for structural characterization. The options for and limitations of studies on the mesoscale are discussed. The list of methods is not complete, but is intended to reflect the methods commonly used in materials science. This survey is followed by an account of the properties of hard x-raysdefined as x-rays with an energy of or above 50 keV -and the utilization of these at hard x-ray synchrotron beamlines. To put the development of the 3DXRD microscope into perspective, a brief account is given of the historical development of the use of such beamlines, with the prime focus initially on macroscale problems in condensed-matter physics. Electron and Optical MicroscopyThe predominant set of tools for structural characterization today belong to the family of electron microscopy (EM). Thanks to its atomic-scale resolution, transmission electron microscopy (TEM) is an indispensable tool for studies of dislocation structures, precipitates, interfaces and nanoscale structures in general [1]. Scanning electron microscopy (SEM) , on the other hand, offers relatively easy sample preparation, larger inspection areas and very userfriendly measurements, but at the cost of a spatial resolution of 1-50 nm [2].Within the last decade, SEM studies in combination with the automatic electron back-scattering pattern (EBSP) method [3,4,5,6] have become the workhorse for many metallurgical studies. The EBSP method, also known as EBSD, enables determination of the crystallographic orientation of selected local areas and reveals the microstructure by orientation contrast. When it is used in conventional SEMs, the spatial resolution is about 0.5-1 µm, whereas field-emission-gun SEMs may give resolutions as high as 50 nm [7]. A limitation for certain studies may be the angular resolution of the orientation determination, which presently is 0.5 0 -1 0 . Despite the enormous impact of EM, it is well recognized that using electrons as a probe is associated with a set of inherent disadvantages. Firstly, probing the elastic and plastic strain by EM is notoriously difficult. Secondly, the dynamical scattering processes involved complicate the process of structural refinement on the basis of diffraction data. Thirdly, the electrons penetrate ≤ 1 µm into materials, such that only the surface region is probed. This fact implies a number of limitations, which are central to this book. They are discussed in detail below.1. 2D characterization. The structural objects of interest, i.e. grains, dislocation structures, cracks, etc., are in general truly three-dimensional in nature. On the basis of observations from a single section, it is only possible to provide a 3D description by subjecting the objects to a statistical treatment. The discipline of stereology [8] was invented to facilitate such a description. However, it turns out that a number of parameters of interest simply cannot be inferred from a single 2D section without...

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Section: Hard X-ray Work Using Synchrotron Sourcesmentioning

confidence: 99%

Methods for Mesoscale Structural Characterization

Poulsen

2004

Springer Tracts in Modern Physics

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“…In this paper, the materials and the methods we used will be described. Then, we will present the indepth mechanical residual tensor which was calculated using dispersive energy method [1,5].…”

Section: Introductionmentioning

confidence: 99%

Evaluation by Synchrotron Radiation of Shape Factor Effects on Residual Stress in Nitrided Layers

Goret

Fabre

Barrallier

et al. 2006

MSF

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Nitriding is a thermo-chemical treatment to improve fatigue life of steel parts what are exposed to high cyclic loading on and close to the surface like gears for example. During the nitrogen diffusion, the precipitation of nitrides and carbides generates residual stresses and increases the superficial hardness. These residual stresses are function of the conditions of the nitriding process but also critically depend on the geometry of the steel components. Indeed, the result of the diffusion process is different for a plane geometry or a curvilinear one. In this present work, the sample is a part of a gear, composed by two teeth. Between two teeth of gear, the determination of in-depth stress gradients by classical X-rays diffraction cannot be done with a great accuracy: the spatial resolution is not sufficient because the irradiated area has the same dimension than the surface curvature of the component. Furthermore, it is very difficult to take into account the removal of matter that is required to determine in-depth stress profile because of the particular geometry. The synchrotron diffraction technique is a well-adapted method to determine such stress gradients in strongly absorbing materials due to the capability of penetration power of high energy X-rays. The removal of matter is not required and it is possible to determine an in-depth map of the stress tensor. After measurements on the ESRF ID15 beam line, stress profile has been calculated without the σ33 equal to zero hypothesis. The results are as following: compressive residual stresses were found close to the surface, and the calculated σ33 component of stress tensor is really not equal to zero. This important result seems to show the geometrical effect on stress state near non-plane surface.

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In-Situ Analysis of Microstress and Texture Development during Tensile Deformation of MMCs at Room Temperature and at Elevated Temperatures Using Synchrotron Radiation

Cited by 2 publications

References 0 publications

Methods for Mesoscale Structural Characterization

Methods for Mesoscale Structural Characterization

Evaluation by Synchrotron Radiation of Shape Factor Effects on Residual Stress in Nitrided Layers

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