AlCoNiFeCrTiVx High-Entropy Coatings Prepared by Electron-Beam Cladding

This is a post-peer-review, pre-copyedit version of an article published in "A. D. Pogrebnjak and O. Bondar (eds.), Microstructure and Properties of Micro- and Nanoscale Materials, Films, and Coatings (NAP 2019), Springer Proceedings in Physics 240". The final authenticated version is available online at: https://doi.org/10.1007/978-981-15-1742-6_16.This study reports the investigation of high-entropy coatings obtained by electron-beam cladding in a vacuum of Al-Co-Ni-Fe-Cr-Ti-Vx powder blend on a steel substrate. V was added to the Al-Co-Ni-Fe-Cr-Ti equiatomic system and the effects of this added element on structure, phase composition and microhardness of AlCoNiFeCrTiVx high entropy coatings resulted from electron beam cladding were studied. The AlCoNiFeCrTiV0 coatings consist of two solid solutions with BCC1 and BCC structure with different lattice parameters and a small volume fraction of σ-phase. It was shown that with an increase in V content from x = 0 to x = 1.5, the phase composition of the coatings transforms from two solid solutions to single BCC solid solution and σ-phases of different compositions. The σ-phase volume fraction increased with an increase in the V content. The addition of V to AlCoNiFeCrTi shows the strengthening effect of the AlCoNiFeCrTiV0.5–1.5 coatings and the Vickers hardness increased from 8.4 to 11 GPa. Microhardness of the coatings was affected by the sigma phase. The hardness enhancement can be likely attributed to the effect of solid solution strengthening and to the presence of σ-phase particles in the coating structure