header

Mechanical Properties and Microstructures after Abnormal Grain Growth in Electrodeposited Ni-W Alloys

31 Pages Posted: 7 Aug 2019 First Look: Accepted

See all articles by Isao Matsui

Isao Matsui

National Institute of Advanced Industrial Science and Technology (AIST) - Structural Materials Research Institute

Atsuya Watanabe

Osaka Prefecture University - Department of Materials Science

Tokuteru Uesugi

Osaka Prefecture University - Department of Materials Science

Naoki Omura

National Institute of Advanced Industrial Science and Technology (AIST) - Structural Materials Research Institute

Yorinobu Takigawa

Osaka Prefecture University - Department of Materials Science

Takahisa Yamamoto

Nagoya University - Department of Materials Design Innovation Engine

Abstract

The thermal stability of electrodeposited Ni-W alloys has been identified to be due to W segregation. Although a kinetic contribution has been recently proposed, namely, the formation of W-oxides at grain boundaries (GBs) by annealing, the formation mechanism is unclear. In this study, we annealed electrodeposited Ni-W alloys up to 600 °C; then, we examined the mechanical properties and microstructures to deeply understand the thermal stability of Ni-W alloys. Mechanical testing of annealed alloys demonstrated that the proof stress and hardness increased against the increase in annealing temperature in the range of 380-450 °C. At the mesoscale, microstructure observations revealed that the grain size was refined with increasing temperature from 390 to 450 °C. Finer-grained microstructures were maintained up to the annealing temperature of 520 °C. At the nanoscale, grain boundary structures were directly observed, and the chemistry was also demonstrated. These nanoscale analyses detected S segregation at GBs and triple junctions, whereas oxides and precipitates likely to affect grain growth were not identified. Our results and discussion indicate that grain refinements against an increase in the annealing temperature can be explained by the conventional relationship between the annealing temperature and nucleation number.

Keywords: electrodeposition, Ni-W alloys, mechanical properties, annealing, grain boundary

Suggested Citation

Matsui, Isao and Watanabe, Atsuya and Uesugi, Tokuteru and Omura, Naoki and Takigawa, Yorinobu and Yamamoto, Takahisa, Mechanical Properties and Microstructures after Abnormal Grain Growth in Electrodeposited Ni-W Alloys (August 4, 2019). Available at SSRN: https://ssrn.com/abstract=3431838 or http://dx.doi.org/10.2139/ssrn.3431838

Isao Matsui (Contact Author)

National Institute of Advanced Industrial Science and Technology (AIST) - Structural Materials Research Institute ( email )

Japan

Atsuya Watanabe

Osaka Prefecture University - Department of Materials Science

Japan

Tokuteru Uesugi

Osaka Prefecture University - Department of Materials Science

Japan

Naoki Omura

National Institute of Advanced Industrial Science and Technology (AIST) - Structural Materials Research Institute

Japan

Yorinobu Takigawa

Osaka Prefecture University - Department of Materials Science

Japan

Takahisa Yamamoto

Nagoya University - Department of Materials Design Innovation Engine

Japan

Here is the Coronavirus
related research on SSRN

Paper statistics

Abstract Views
165
Downloads
21