Halo formation of Zn-Al alloys under conventional solidification and intensive convection solidification
| Autor: | Wenchao Yang, Shouxun Ji, Hasse Fredriksson |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Convection Materials science Mechanical Engineering Metallurgy Metals and Alloys Crystal growth 02 engineering and technology 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Strain energy Mechanics of Materials Phase (matter) 0103 physical sciences Materials Chemistry Halo 0210 nano-technology Elastic modulus Eutectic system |
| Zdroj: | Journal of Alloys and Compounds. 696:460-469 |
| ISSN: | 0925-8388 |
| Popis: | A halo occurred usually as an envelope of one phase around a primary phase in many alloys after solidification. Its formation mechanism was investigated for hypoeutectic, eutectic and hypereutectic compositions of Zn-Al alloys under conventional solidification and under intensive convection solidification. It was found that the Zn-rich halos occurred in the surroundings of the Al-rich primary phase for the hypereutectic Zn-Al alloys at Al>5 wt% and no halos occurred for the hypoeutectic and eutectic Zn-Al alloys at Al≤5 wt% under conventional solidification. However, the Zn-rich halos were completely absent from the Al-rich phase because of the uniform temperature distribution and enhanced mass transport under intensive convection solidification. Once the intensive convection was interrupted during solidification for the solid-liquid co-existing melt, a halo was formed on the surface of the existing Al-rich phase created either during the primary solidification or the eutectic solidification. Therefore, it was concluded that the halo formation should be a growth-dominant phenomenon not a nucleation-dominant phenomenon. And, the interaction among the solid phases and the liquid phase was responsible for the halo formation, in which the difference in the elasticity modulus and the density of the different phases resulted in the variation of strain energy in the individual phase. |
| Databáze: | OpenAIRE |
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