Characterization of phase transformation behaviour and microstructural development of electroless Ni-B coating

Pal, Soupitak and Verma, Nisha and Jayaram, Vikram and Biswas, Sanjay Kumar and Riddle, Yancy (2011) Characterization of phase transformation behaviour and microstructural development of electroless Ni-B coating. In: Materials Science and Engineering A, 528 (28). pp. 8269-8276.

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Abstract

Phase transformation behaviour of amorphous electroless Ni-B coating with a targeted composition of Ni-6wt% B is characterized in conjunction with microstructural development and hardness. Microscopic observations of the as-deposited coating display a novel microstructure which is already phase separated at multiple length scales. Spherical colonies of similar to 5 mu m consist of 2-3 mu m nodular regions which are surrounded by similar to 2-3 mu m region that contains fine bands ranging from 10 to 70 nm in width. The appearance of three crystalline phases in this binary system at different stages of heat treatment and the concomitant variation in hardness are shown to arise from nanoscale fluctuations in the as-deposited boron content from 4 to 8 wt%. High temperature annealing reveals continuous crystallization up to 430 degrees C, overlapping with the domain of B loss due to diffusion into the substrate. The implications of such a microstructure for optimal heat treatment procedures are discussed. (C) 2011 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	Materials Science and Engineering A
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	X-ray diffraction;Electron microscopy;Nanostructured materials;Phase transformation
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	04 Nov 2011 09:33
Last Modified:	04 Nov 2011 09:33
URI:	http://eprints.iisc.ac.in/id/eprint/41819

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