Hardness and microstructure of tungsten heavy alloy subjected to severe plastic deformation and post-processing heat treatment
The hardness and thermal stability of 90W–8Ni–2Fe tungsten heavy alloy (WHA), following severe plastic deformation by equal channel angular extrusion, are reported. Square bars measuring 25×25×150mm3 were processed at 300°C to plastic strains of 2.68. The hardness of WHA increased with increased str...
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Veröffentlicht in: | Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2015-05, Vol.635, p.94-101 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The hardness and thermal stability of 90W–8Ni–2Fe tungsten heavy alloy (WHA), following severe plastic deformation by equal channel angular extrusion, are reported. Square bars measuring 25×25×150mm3 were processed at 300°C to plastic strains of 2.68. The hardness of WHA increased with increased strain, from 29 Rockwell Hardness C (HRC) in the as-received condition, to ~50 HRC. ECAE refined the grain size of the tungsten particles from tens of microns to 270nm. This decrease in tungsten grain size correlates with the increase in hardness following a Hall–Petch relationship. Annealing results indicate that the matrix phase recrystallizes at 500°C, while the tungsten-rich phase begins to recrystallize at near ~800°C. The morphology of the tungsten-rich particles changes from near-spherical to elongated platelets or ellipsoids, depending on processing strain path. The results suggest ECAE is an effective technique for manipulating the microstructure, phase morphology, and mechanical properties of WHA. |
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ISSN: | 0921-5093 1873-4936 |
DOI: | 10.1016/j.msea.2015.02.025 |