Diffusion and Defect Data Solid State Data Part B Solid State Phenomena, 2005
Page 1. Residual strain and texture measurements using neutron-TOF-diffraction on a dolomite-anhy... more Page 1. Residual strain and texture measurements using neutron-TOF-diffraction on a dolomite-anhydrite rock and a quartz-dunite compound Scheffzük, Ch. 1,2 , Walther, K. 1 , Frischbutter, A. 1 , Eichhorn, F. 3 & Daymond, MR 4 ...
In situ synchrotron X-ray diffraction has been used to determine strain evolution in a minority p... more In situ synchrotron X-ray diffraction has been used to determine strain evolution in a minority phase, zirconium hydride, embedded in Zircaloy-2 (<100 wt ppm average hydrogen content). The elastic modulus of the hydride is similar to that of Zircaloy-2. Three regimes are observed: I - elastic, II - post-yield load transfer from Zircaloy-2 to hydride, and III - strain saturation, possibly due to hydride fracture. The interpretation is supported by finite element calculations and scanning electron microscopy of the fracture surface.
Conventional deformation experiments on polycrystalline materials are restricted to measurements ... more Conventional deformation experiments on polycrystalline materials are restricted to measurements of whole sample properties. This is a significant limitation for problems where it is important to know how the deformation is accommodated at the grain scale in order to interpret the experimental results and compare them with theoretical treatments. Such problems include (a) characterizing the properties of elastically anisotropic materials, where it is helpful to know the elastic strain in different lattice directions of the constituent minerals, and how this varies with microstructural variables such as the lattice preferred orientation of those minerals; (b) characterizing the mechanical properties of polymineralic materials in terms of the properties of their constituent minerals, where it is helpful to know the contribution which each mineral phase makes to the whole rock properties during deformation and how this varies with microstructural variables such as the spatial distribution of those phases; (c) calibrating stress-induced crystallographic transformations (e.g., mechanical twinning) where it is important to monitor closely the initiation and progress of the transformation as a function of applied stress. By performing deformation experiments in-situ within neutron beam-lines and collecting neutron diffraction patterns at different applied loads, the lattice parameters of all the constituent minerals in the sample may be determined as a function of load. All the requisite information required to address the three problems above may then be obtained. The value of such an approach is much diminished if in obtaining the data, compromises have to be made in the quality of the mechanical measurements. This is particularly so if the diffraction data have to be collected either from small samples or from near surface parts of the sample because the interpretation of the mechanical data in such circumstances is notoriously difficult. In this respect, the penetrating nature of neutrons offers significant advantages over X-rays by permitting the interior of samples of the same size as used in conventional rock deformation experiments to be examined. An experimental procedure for carrying out such experiments has been developed at the ISIS neutron spallation source, Rutherford Appleton Laboratory, U.K., and has been applied successfully to both synthetic and natural samples containing a wide range of rock-forming minerals. The validity of the technique is demonstrated using results from uniaxial deformation experiments performed on olivine + magnesiowustite samples, and current progress in using it to address each of the three problems outlined above is described.
Conventional deformation experiments are generally restricted to the measurement of whole sample ... more Conventional deformation experiments are generally restricted to the measurement of whole sample properties, but performing such experiments in situ within a neutron beamline makes it possible to determine how this deformation is accommodated at the grain scale within the sample. By collecting neutron diffraction patterns at different applied loads, the change in lattice parameters (and from this the elastic strain) of each mineral phase present may be monitored during the experiment. Moreover, changes in microstructural properties, such as developing textures and the progress of any mineral transformations, can be monitored. We have performed axial compression experiments on large samples using the ENGIN-X beamline at ISIS to explore the potential of this approach for characterizing the mechanical properties of geological materials. Recent developments to our experimental methodologies include the ability to perform experiments at temperatures up to 800 K and confining pressures up to 200 MPa, using a newly designed pressure vessel. These methods enable us to explore phenomena such as elastic anisotropy in rocks, changes in strain partitioning during plastic yielding, and stress-induced mechanical twinning.
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, Jun 1, 2006
The response of 316 stainless steel has been examined under uniaxial tensile loading during a ran... more The response of 316 stainless steel has been examined under uniaxial tensile loading during a range of tests carried out between 20 °C and 650 °C. In-situ neutron diffraction was used to measure internal elastic strain in subsets of differently oriented crystallites within the polycrystal aggregate. This allowed the determination of diffraction elastic constants. Further, results have been compared with predictions from a slip-based elasto-plastic self-consistent model. Good agreement is obtained during both conventional slip and when dynamic strain aging (DSA) is evidenced. The quality of agreement was reduced in the higher temperature regime, where it is expected that other mechanisms become active.
Diffusion and Defect Data Solid State Data Part B Solid State Phenomena, 2005
Page 1. Residual strain and texture measurements using neutron-TOF-diffraction on a dolomite-anhy... more Page 1. Residual strain and texture measurements using neutron-TOF-diffraction on a dolomite-anhydrite rock and a quartz-dunite compound Scheffzük, Ch. 1,2 , Walther, K. 1 , Frischbutter, A. 1 , Eichhorn, F. 3 &amp; Daymond, MR 4 ...
In situ synchrotron X-ray diffraction has been used to determine strain evolution in a minority p... more In situ synchrotron X-ray diffraction has been used to determine strain evolution in a minority phase, zirconium hydride, embedded in Zircaloy-2 (<100 wt ppm average hydrogen content). The elastic modulus of the hydride is similar to that of Zircaloy-2. Three regimes are observed: I - elastic, II - post-yield load transfer from Zircaloy-2 to hydride, and III - strain saturation, possibly due to hydride fracture. The interpretation is supported by finite element calculations and scanning electron microscopy of the fracture surface.
Conventional deformation experiments on polycrystalline materials are restricted to measurements ... more Conventional deformation experiments on polycrystalline materials are restricted to measurements of whole sample properties. This is a significant limitation for problems where it is important to know how the deformation is accommodated at the grain scale in order to interpret the experimental results and compare them with theoretical treatments. Such problems include (a) characterizing the properties of elastically anisotropic materials, where it is helpful to know the elastic strain in different lattice directions of the constituent minerals, and how this varies with microstructural variables such as the lattice preferred orientation of those minerals; (b) characterizing the mechanical properties of polymineralic materials in terms of the properties of their constituent minerals, where it is helpful to know the contribution which each mineral phase makes to the whole rock properties during deformation and how this varies with microstructural variables such as the spatial distribution of those phases; (c) calibrating stress-induced crystallographic transformations (e.g., mechanical twinning) where it is important to monitor closely the initiation and progress of the transformation as a function of applied stress. By performing deformation experiments in-situ within neutron beam-lines and collecting neutron diffraction patterns at different applied loads, the lattice parameters of all the constituent minerals in the sample may be determined as a function of load. All the requisite information required to address the three problems above may then be obtained. The value of such an approach is much diminished if in obtaining the data, compromises have to be made in the quality of the mechanical measurements. This is particularly so if the diffraction data have to be collected either from small samples or from near surface parts of the sample because the interpretation of the mechanical data in such circumstances is notoriously difficult. In this respect, the penetrating nature of neutrons offers significant advantages over X-rays by permitting the interior of samples of the same size as used in conventional rock deformation experiments to be examined. An experimental procedure for carrying out such experiments has been developed at the ISIS neutron spallation source, Rutherford Appleton Laboratory, U.K., and has been applied successfully to both synthetic and natural samples containing a wide range of rock-forming minerals. The validity of the technique is demonstrated using results from uniaxial deformation experiments performed on olivine + magnesiowustite samples, and current progress in using it to address each of the three problems outlined above is described.
Conventional deformation experiments are generally restricted to the measurement of whole sample ... more Conventional deformation experiments are generally restricted to the measurement of whole sample properties, but performing such experiments in situ within a neutron beamline makes it possible to determine how this deformation is accommodated at the grain scale within the sample. By collecting neutron diffraction patterns at different applied loads, the change in lattice parameters (and from this the elastic strain) of each mineral phase present may be monitored during the experiment. Moreover, changes in microstructural properties, such as developing textures and the progress of any mineral transformations, can be monitored. We have performed axial compression experiments on large samples using the ENGIN-X beamline at ISIS to explore the potential of this approach for characterizing the mechanical properties of geological materials. Recent developments to our experimental methodologies include the ability to perform experiments at temperatures up to 800 K and confining pressures up to 200 MPa, using a newly designed pressure vessel. These methods enable us to explore phenomena such as elastic anisotropy in rocks, changes in strain partitioning during plastic yielding, and stress-induced mechanical twinning.
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, Jun 1, 2006
The response of 316 stainless steel has been examined under uniaxial tensile loading during a ran... more The response of 316 stainless steel has been examined under uniaxial tensile loading during a range of tests carried out between 20 °C and 650 °C. In-situ neutron diffraction was used to measure internal elastic strain in subsets of differently oriented crystallites within the polycrystal aggregate. This allowed the determination of diffraction elastic constants. Further, results have been compared with predictions from a slip-based elasto-plastic self-consistent model. Good agreement is obtained during both conventional slip and when dynamic strain aging (DSA) is evidenced. The quality of agreement was reduced in the higher temperature regime, where it is expected that other mechanisms become active.
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