| Autor: |
Li, Lei, Liang, Wenlei, Yang, Lin, Cao, Fanglin, Sun, Ke, Ban, Chunyan, Cui, Jianzhong |
| Zdroj: |
International Journal of Metalcasting; January 2023, Vol. 17 Issue: 1 p399-413, 15p |
| Abstrakt: |
Due to the structural inheritance, a uniform and refined as-cast microstructure is usually desirable for further thermomechanical processing of biodegradable Zn alloys. Considering the effectiveness of pulsed magnetic field (PMF) for structure refinement and homogenization, a high-voltage PMF was applied to the solidification process of Zn-Cu alloys with different compositions in this work. For Zn-1.5Cu alloy, a 6 kV PMF (i.e., a PMF generated by a discharge voltage of 6 kV) transformed the macrostructure from a mixture of coarse columnar and equiaxed η-Zn grains with an average size of 1437 ± 482 μm to homogeneously distributed fine equiaxed η-Zn grains with an average size of 454 ± 15 μm. For Zn-2.5Cu alloy, a 6 kV PMF changed the long dendritic primary ɛ-CuZn4particles into fine dot-like particles. Correspondingly, the coarse equiaxed η-Zn grains with an average size of 1895 ± 375 μm are transformed to fine equiaxed ones with an average size of 446 ± 46 μm due to the increase in amount of the primary ɛ-CuZn4particles as potent heterogeneous nucleation sites. For Zn-4.0Cu alloy, a 6 kV PMF causes segregation of the primary ɛ-CuZn4particles at the lower part of the specimen and intensifies the macrostructural inhomogeneity. For all the alloys, the most significant effect of the PMF on structure refinement and homogenization occurs in the early stage of solidification. The convection and Joule heat induced by the PMF in the melt are responsible for the structural transformation. |
| Databáze: |
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