MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
Formation of Inter-Diffusion Layer between NiCrAlY Coating and Nb Substrate during Vacuum Heat-Treatment
Shigeru SaitoToshiyuki TakashimaKatsumi MiyamaToshio NaritaLinruo Zhao
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2015 Volume 56 Issue 3 Pages 367-371

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Abstract

The formation of the inter-diffusion layer between NiCrAlY coating and Nb substrate during vacuum heat treatment was investigated. A NiCrAlY coating was applied on Nb substrate by cathode arc deposition. Vacuum heat treatments were carried out at 800, 900, and 1000°C for 2 h. SEM, EPMA, EDS, and XRD were performed to analyze the microstructure of the inter-diffusion layer and the results were interpreted using the 1002°C isothermal ternary Nb-Ni-Cr phase diagram. It was found that at 800°C the inter-diffusion layer has a single NbNi3 layer; at 900°C the inter-diffusion layer consists of an outer NbNi3 layer, a thin intermediate NbCr2(HT) layer, and an inner Nb7Ni6 layer; at 1000°C the inter-diffusion layer has three well-developed layers of an outer NbNi3 layer, an inner Nb7Ni6 layer, and an intermediate layers comprising NbCr2(HT) and NbNi3. A small amount of Cr exists in both the NbNi3 and the Nb7Ni6 phases as solid solution, and a large amount of Ni in the NbCr2(HT) phase as solid solution.

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© 2015 The Japan Institute of Metals and Materials
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