TY - GEN
T1 - Density of stacking faults and twin boundaries in ultrafine-grained materials determined by X-ray line profile analysis
AU - Ungár, Tamás
AU - Balogh, Levente
AU - Zhu, Yuntian T.
AU - Xu, Cheng
AU - Ribárik, Gábor
AU - Horita, Zenji
AU - Langdon, Terence G.
PY - 2006/5/18
Y1 - 2006/5/18
N2 - Planar faults, especially stacking faults and twins, can play an important role in the defect structure of ultrafme-grained materials. X-ray line broadening and line shift caused by planar faults is highly anisotropic as a function of the hkl indices, the anisotropy being qualitatively different from both strain and size anisotropy. This makes it possible to distinguish the line broadening components corresponding to planar faults, dislocations and subgrain size. The numerical procedure, the CMWP (convolutional multiple whole profile) method for the evaluation of diffraction patterns based on the model of dislocations and grain size for strain and size broadening, has been extended for the evaluation of planar faults present concomitantly with dislocations and subgrains. The effect of planar faults on diffraction profiles has been evaluated numerically by using the DIFFAX software. About 15.000 diffraction profiles have been produced for intrinsic, extrinsic and twin faults as a function of different hkl indices and planar fault concentrations. It was found that the numerically calculated diffraction profiles can be well simulated by Lorentzian functions as far as down to 104 relative intensities into the tails. Thus, about 15.000 simulated Lorentzians have been systematically parameterized for hkl fault types and fault densities, respectively, and the compiled parameter files have been incorporated into the CMWP numerical procedure; The dislocation structure, the subgrain size and size distribution and the densities of twin boundaries have been determined in specimens of Cu and Cu-Zn alloys processed by high-pressure torsion as a function of the distance along the radius of the samples.
AB - Planar faults, especially stacking faults and twins, can play an important role in the defect structure of ultrafme-grained materials. X-ray line broadening and line shift caused by planar faults is highly anisotropic as a function of the hkl indices, the anisotropy being qualitatively different from both strain and size anisotropy. This makes it possible to distinguish the line broadening components corresponding to planar faults, dislocations and subgrain size. The numerical procedure, the CMWP (convolutional multiple whole profile) method for the evaluation of diffraction patterns based on the model of dislocations and grain size for strain and size broadening, has been extended for the evaluation of planar faults present concomitantly with dislocations and subgrains. The effect of planar faults on diffraction profiles has been evaluated numerically by using the DIFFAX software. About 15.000 diffraction profiles have been produced for intrinsic, extrinsic and twin faults as a function of different hkl indices and planar fault concentrations. It was found that the numerically calculated diffraction profiles can be well simulated by Lorentzian functions as far as down to 104 relative intensities into the tails. Thus, about 15.000 simulated Lorentzians have been systematically parameterized for hkl fault types and fault densities, respectively, and the compiled parameter files have been incorporated into the CMWP numerical procedure; The dislocation structure, the subgrain size and size distribution and the densities of twin boundaries have been determined in specimens of Cu and Cu-Zn alloys processed by high-pressure torsion as a function of the distance along the radius of the samples.
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M3 - Conference contribution
AN - SCOPUS:33646500992
SN - 0873396286
SN - 9780873396288
T3 - TMS Annual Meeting
SP - 483
EP - 490
BT - Ultrafine Grained Materials IV
T2 - 2006 TMS Annual Meeting
Y2 - 12 March 2006 through 16 March 2006
ER -