Grain boundary diffusion of chromium in polycrystalline nickel studied by SIMS

Abstract : The grain boundary diffusion of chromium in polycrystalline nickel was studied by means of tracer experiments at 346-668 °C. Intensity-depth profiles were recorded by secondary ion mass spectrometry (SIMS), which allowed short diffusion distances, and therefore relatively low temperatures, to be examined. Individual grain boundaries in coarse-grained substrates produced profiles with a variety of shapes, reflecting the variability of diffusivities in a polycrystal, and even within a grain boundary. Average diffusivities were also measured using cold-rolled substrates, which rapidly recrystallized and provided finer microstructures. The simplifying assumptions usually made in processing B regime data were found not to be applicable here, because of the shallow measurement depths. The errors made by using approximate solutions to the diffusion equation are discussed, and a data processing method adapted to the conditions of SIMS measurements is used. A method to study diffusion tails with smooth slope variations is also demonstrated. The measured diffusivities were found to be in agreement with higher temperature data from the literature.
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Submitted on : Tuesday, November 5, 2019 - 10:07:33 PM
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Thomas Gheno, François Jomard, Clara Desgranges, Laure Martinelli. Grain boundary diffusion of chromium in polycrystalline nickel studied by SIMS. Materialia, Elsevier, 2019, 6, pp.100283. ⟨10.1016/j.mtla.2019.100283⟩. ⟨hal-02350066⟩

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