Effect of Cr particle size on the development of a chromia scale on Ni-Cr composites

摘要

The nanocystalline Ni-base composites dispersing Cr particles in different size range were deliberately fabricated. It showed that the Cr content for chromia scale formation at 900 degrees C decreased from above 20 wt% required by the microparticle (-4 pm in size) dispersed composite to much lower values of 13 wt% and 7.8 wt% required by the composites dispersing submicron- (-0.8 pm) and nanoparticles (-25 nm), respectively. The particle size effect on oxidation, primarily resulting from the finer Cr dispersions which favor more ubiquitous chromia nucleation when oxidation starts, offers a guideline for designing and manufacturing low-Cr containing but oxidation-resistant alloys.

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