The influence of oxygen contamination on the thermal stability and hardness of nanocrystalline Ni–W alloys
| Autor: | Martin P. Harmer, Patrick R. Cantwell, Christopher J. Marvel, Denise Yin |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
010302 applied physics
Materials science Annealing (metallurgy) Mechanical Engineering Metallurgy Oxide 02 engineering and technology Nanoindentation 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Indentation hardness Nanocrystalline material Grain growth chemistry.chemical_compound Chemical engineering chemistry Mechanics of Materials 0103 physical sciences General Materials Science Grain boundary Thermal stability 0210 nano-technology |
| Zdroj: | Materials Science and Engineering: A. 664:49-57 |
| ISSN: | 0921-5093 |
| DOI: | 10.1016/j.msea.2016.03.129 |
| Popis: | Nanocrystalline Ni–W alloys are reported in the literature to be stabilized against high temperature grain growth by W-segregation at the grain boundaries. However, alternative thermal stability mechanisms have been insufficiently investigated, especially in the presence of impurities. This study explored the influence of oxygen impurities on the thermal stability and mechanical properties of electrodeposited Ni-23 at% W with aberration-corrected scanning transmission electron microscopy (STEM) and nanoindentation hardness testing. The primary finding of this study was that nanoscale oxides were of sufficient size and volume fraction to inhibit grain growth. The oxide particles were predominantly located on grain boundaries and triple points, which strongly suggests that a particle drag mechanism was active during annealing. In addition, W-segregation was observed at the oxide/Ni(W) interfaces rather than the presumed Ni(W) grain boundaries, further supporting the argument that alternative mechanisms are responsible for thermal stability in these alloys. Lastly, alloys with nanoscale oxides exhibited a higher hardness compared to similar alloys without oxides, suggesting that the particles are widely advantageous. Overall, this work demonstrates that impurity oxide particles can limit grain growth, and alternative mechanisms may be responsible for Ni–W thermal stability. |
| Databáze: | OpenAIRE |
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