Influences of arc current on microstructure of Cr coating for Zr-4 alloy prepared by multi-arc ion plating via EBSD

The present work is aimed to investigate the influences of arc current on the microstructure evolution of the as-deposited Cr coatings for accident tolerant fuel. Cr coatings were prepared on the surface of Zr-4 alloy by multi-arc ion plating with different arc currents. Electron backscattering diffraction (EBSD) technology was employed to characterize the microstructure evolution of the as-deposited Cr coatings, including the distribution of grain boundaries, the mean grain size, the crystallographic orientation distribution, the dislocation density and dynamic recrystallization (DRX). The results showed that: regarding the mean grain size of the Cr coating, the largest was that prepared by 80A, followed by 100A, 70A and 90A; regarding the number fraction of HAGBs, the highest was that prepared by 80A, followed by 90A, 100A and 70A; regarding the grain morphology, the Cr coating prepared by 70A exhibited equiaxed grains without obvious texture, while that prepared by 80A, 90A and 100A had elongated columnar grains along the building direction; regarding the crystal phase, the Cr coating prepared by 80A, 90A and 100A exhibited the (100)〈001〉 texture component; regarding the dislocation density, there was a large number of scattered high dislocation density regions in the Cr coating prepared by 70A, the high dislocation density regions only appeared on the surface layer in the Cr coating prepared by 90A, and along the boundaries of elongated grains in the Cr coating prepared by 100A, while it was almost non-existent in the Cr coating prepared by 80A; regarding the DRX, discontinues DRX (DDRX) was the principal DRX mechanism for the Cr coating prepared by 70A, while continues DRX (CDRX) was the dominant DRX mechanism for the Cr coatings prepared by 80A, 90A and 100A.