Seminar by Prof. Tamas UNGAR “Microstrain from X-ray and neutron line broadening in terms of dislocation structure related to mechanical properties”


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Date | Time
19/10/2015 | 11 h 00 min - 12 h 30 min

Location
Salle Klepaczko

Categories


Abstract:

Diffraction peaks of X-ray or neutron diffraction patterns broaden when the dislocation density exceeds about 5×10^12 m-2, the average grain or subgrain size is smaller than about 1 micron or the average distance of planer defects, twin boundaries or stacking faults, is shorter than about 1 micron. Defect specific hkl dependence enables to separate the different contribution to peak broadening. TOF neutron diffraction patterns were measured in the VULCAN beamline at SNS of Oak Ridge National Laboratory on tensile strained 316 stainless steel specimen. The data were analyzed in terms of the alfa parameter in Taylor’s equation. Dislocation densities were determined in the different texture components of a plastically deformed Zircaloy specimen in the SMARTS neutron diffractometer at the Los Alamos National Laboratory. Slip-modes and slip-systems were determined in individual grains in polycrystalline aggregates of CoTi and CoZr from synchrotron diffraction patterns measured at the APS at Argonne National Laboratory.