MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
Comparison of Tensile Properties of Bulk Nanocrystalline Ni–W Alloys Electrodeposited by Direct, Pulsed, and Pulsed-Reverse Currents
Isao MatsuiNaoki Omura
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2018 Volume 59 Issue 1 Pages 123-128

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Abstract

The effects of current types on the microstructure and tensile properties of electrodeposited bulk nanocrystalline Ni–W alloys were studied. We electrodeposited bulk Ni–W alloys using direct current, pulsed current, and pulsed-reverse current. We measured the W content of the resulting samples to be in the range of 0.8–2.2 at%. An increase in the peak current density or the use of a reverse current reduced the W content. The reduction of W content increased the grain size from 26 to 40 nm. The hardness and yield strength increased as the grain size decreased. However, tensile elongation showed no dependence on grain size or W content. Most alloys exhibited a similar uniform elongation of approximately 5%, while the local elongation varied from 0.1% to 6.9%. The application of a pulsed current increased the peak current density and reduced the tensile elongation. The use of a reverse current stripped the surface of deposits formed during electrodeposition, resulting in higher tensile elongation at the same peak current densities. The results of this study indicate the effectiveness of a reverse current in electrodeposition for adjusting solute content and reducing processing defects.

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© 2017 The Japan Institute of Metals and Materials
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