Virtual Labs

Dislocation density measurement in cold rolled metals using XRD and TEM

In XRD, why do dislocations in cold-rolled metals cause peak broadening?

a: They strongly absorb incident X-rays Explanation

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b: They create lattice distortions and micro-strains Explanation

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c: They reduce the number of diffraction planes Explanation

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d: They completely change the crystal structure Explanation

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Which line-broadening analysis method is commonly used to estimate dislocation density from XRD data?

a: Rietveld refinement Explanation

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b: EDS mapping Explanation

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c: Williamson-Hall plotting Explanation

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d: EBSD indexing Explanation

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In Transmission Electron Microscopy (TEM), dislocations are visible because they __________.

a: reflect more electrons than the surrounding matrix Explanation

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b: emit X-rays that are detected by the microscope Explanation

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c: cause local contrast differences by bending the lattice planes Explanation

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d: remove atoms completely from the sample Explanation

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To calculate dislocation density using a TEM micrograph, you need to know the total length of dislocation lines and __________.

a: the crystal orientation alone Explanation

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b: the thickness of the sample foil and the imaged area Explanation

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c: the energy of the electron beam Explanation

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d: the chemical composition of the metal Explanation

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Dislocation density is generally expressed in which unit?

a: m⁻² Explanation

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b: atoms/cm³ Explanation

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c: g/cm³ Explanation

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d: N/m Explanation

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In cold-rolled metals, the typical range for high dislocation densities is around __________.

a: 10³ to 10⁵ m⁻² Explanation

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b: 10⁷ to 10⁹ m⁻² Explanation

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c: 10¹⁴ to 10¹⁵ m⁻² Explanation

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d: 10²⁴ to 10²⁶ m⁻² Explanation

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To separate the true peak broadening from instrumental effects in XRD dislocation analysis, researchers typically __________.

a: use the same measurement on multiple instruments Explanation

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b: subtract the instrumental broadening measured with a strain-free reference Explanation

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c: rely solely on TEM images for correction Explanation

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d: ignore instrumental broadening as it is negligible Explanation

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