Scanning positron microscopy: Non-destructive imaging of plastic deformation in the micrometer range

Haaks, M.

doi:10.1016/j.cirp.2008.03.109

Cited by 6 publications

(2 citation statements)

References 18 publications

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“…Recently, new observation techniques have been developed in several fields, e.g., 3D tomography in transmission electron microscopy (TEM), 10) orientation imaging microscopy, 11) and positron annihilation. 12) These analyses provide useful detailed information regarding micro-and nanostructures and lattice defects. As is known, electrical resistivity is sensitive to phase transitions and changes in densities of lattice defects.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of Electrical Resistivity in Cold Rolled Ti Sheet

2013

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Observation and evaluation of lattice defects such as vacancy, dislocation and grain boundary are very important for understanding microstructure development during thermo-mechanical treatments. Electrical resistivity measurements are superior to electron microscopies in terms of obtaining average information on micro-and nano-structures including lattice defects. The purpose of this study is to quantify lattice defects and crystallographic features in cold rolled and annealed pure Ti by precise measurements of electrical resistivity. Electrical resistivities at 77 K (liquid nitrogen) and 300 K were measured in a cold rolled Ti sheet at angles of 0, 45, 90°from the rolling direction (RD) by a direct current (DC) four-point method. The resistivity at 90°from RD was slightly higher than that at 0°. A characteristic texture was developed in the sheet; accumulation of (0001) pole was confirmed to appear at an elevation angle of about 40°on the transverse plane. In Matthiessen's empirical relationship for the cold rolled specimens, strong anisotropy in resistivity could also be confirmed. The gradient ¡ and the intercept ¢ values of the relationship might be employed as parameters to quantify the anisotropy of crystal structures and dislocation structures.

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Section: Introductionmentioning

confidence: 99%

Anisotropy of Electrical Resistivity in Cold Rolled Ti Sheet

2013

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“…Thus, understanding the density, character, and behavior of lattice defects such as vacancies, dislocations, and grain boundaries is very important in materials design. Recently, new observation techniques have been developed in several fields, such as 3D tomography in transmission electron microscopy (TEM) 1 , orientation imaging microscopy 2 , and positron annihilation 3 . These methods provide useful and detailed information regarding microstructure and lattice defects 4 .…”

Section: Introductionmentioning

confidence: 99%

Measurement of Electrical Resistivity during Tensile Deformation of Pure Ti

Fujita

Ueda

Ikeda

2014

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The observation and evaluation of lattice defects such as vacancies, dislocations, and grain boundaries are very important in materials design. Electrical resistivity measurement is superior to electron microscopy for obtaining average microstructural information, including density and type of lattice defects. The purpose of this study was to estimate changes in electrical resistivity during the tensile deformation of commercial-purity (CP) Ti. The electrical resistivity of a cold-rolled Ti sheet was measured at 77 K (ρ 77 ) and 300 K (ρ 300 ) along the rolling direction (RD) using a direct current (DC) four-point method to determine Matthiessen's empirical relationship, ρ 77 = α/(R -1) + β, R = ρ 300 /ρ 77 . Plots of ρ 77 versus 1/(R -1) showed a linear relationship, and the values of α and β were determined to be 0.5266 and -0.0024, respectively. Changes in ρ 77 during tensile deformation were estimated by substituting the resistance ratio R into Matthiessen's empirical relationship. In the elastic deformation region, no remarkable change in the resistivity was observed. Therefore, the dislocation density did not change significantly. However, the resistivity did increase drastically near the yield point.

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