Virtual Labs

Electron Micro Probe Analyses of Alloy for Precise Determination of Chemical Composition

Which characterisation technique is used to quantify the chemical composition of an unknown sample in conventional SEM and EPMA?

a: EDX and WDS Explanation

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b: WDS and XRF Explanation

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c: XRD and WDS Explanation

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d: XRF and EDX Explanation

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What are the potential artefacts that can arise from sample charging during EPMA analysis of non-conductive alloy phases, and how can these be mitigated?

a: Sample charging improves X-ray production, enhancing analysis Explanation

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b: Sample charging can lead to beam deflection, localized heating, and distortion of X-ray intensities; mitigate by applying a conductive coating or using low accelerating voltage Explanation

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c: Sample charging has no significant effect on EPMA analysis Explanation

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d: Sample charging can be corrected by post-processing the data Explanation

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Why is it necessary to consider the possibility of beam drift during extended EPMA measurements of alloys?

a: Beam drift enhances the spatial resolution; no mitigation is needed Explanation

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b: Beam drift can cause misalignment of the analysis spot, leading to inaccurate compositional data Explanation

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c: Beam drift only affects imaging, not compositional analysis Explanation

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d: Beam drift can be ignored if the beam current is high enough Explanation

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What are the potential challenges in analyzing light elements such as boron (B) and carbon (C) in alloys using EPMA, and how can these challenges be overcome?

a: Light elements have high X-ray emission efficiency; no special techniques are needed Explanation

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b: Light elements have low X-ray yields and are prone to absorption; overcome by using lower beam energies and applying appropriate ZAF corrections Explanation

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c: Light elements cause detector saturation; mitigate by using reduced beam currents Explanation

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d: They are easily ionized; use cryogenic techniques to stabilize the sample Explanation

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How does the surface roughness of an alloy sample impact the accuracy of EPMA analysis, and what methods can be used to minimize these effects?

a: Surface roughness enhances X-ray production; no need for correction Explanation

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b: Surface roughness can lead to uneven X-ray emission and inaccuracies in composition; mitigate by polishing the sample to a smooth, mirror-like finish Explanation

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c: Surface roughness only affects imaging, not compositional analysis Explanation

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d: Surface roughness can be corrected by software algorithms during post-processing Explanation

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