Eutectic structures in the Ni-Co-Cr-Al system obtained by plasma spraying and by Bridgman growth

摘要

Formation of a regular fibrous two-phase microstructure was found in low-pressure plasma spray (LPPS) deposited Ni-Co-Cr-Al-Y coatings by transmission electron microscopy and analyzed by energy dispersive spectroscopy. The structure is compared to aligned lamellar three-phase structures of an Ni-Co-Cr-Al alloy obtained on Bridgman growth under slow unidirectional solidification (UDS) conditions. The composition of the Ni-Co-Cr-Al alloy for UDS experiments has been identified by DTA. The conditions for the formation of both the LPPS and the UDS structures are discussed.