Microstructure and phase composition of NiAl-CrB₂ composite powders used for plasma spraying

Olena Poliarus, Jerzy Morgiel, Oleksandr Umanskyi, Maciej Szlezynger, Małgorzata Pomorska, Piotr Bobrowski, Maciej Szczerba

Quarterly No. 2, 2018 pages 121-124

DOI:

keywords: NiAl, CrB₂, Ni_0.5Cr_1.5B₃, hot pressing, sintering, microstructure, SEM, XRD

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abstract The preparation of powder agglomerates used in the plasma spray deposition processes, and especially their homogeneity, turned out to be highly important at the moment when the phase ratio in the composite coatings began to differ from that in the starting materials. The present experiment was aimed at comparing the microstructure and phase composition of hot pressed or sintered NiAl and CrB₂ powders. The use of SEM and XRD methods showed that only sintering leads to a reaction of the chromium diboride with the intermetallic matrix. As a result of this process, Ni_0.5Cr_1.5B₃ phase precipitates on the CrB₂ particles. Consequently, the agglomerates formed after crushing the compacts obtained by sintering are much more homogeneous than those formed by hot pressing.