Microstructural evolution and mechanical properties of Al-7Si-0.3Mg alloys with erbium additions
| Autor: | Chaowalit Limmaneevichitr, Ussadawut Patakham, Phromphong Pandee |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010302 applied physics
Acicular Materials science Mechanical Engineering Metallurgy Alloy Metals and Alloys Nucleation 02 engineering and technology engineering.material 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Grain size law.invention Dendrite (crystal) Optical microscope Mechanics of Materials law 0103 physical sciences Materials Chemistry engineering 0210 nano-technology Eutectic system |
| Zdroj: | Journal of Alloys and Compounds. 728:844-853 |
| ISSN: | 0925-8388 |
| Popis: | The mechanical properties of hypoeutectic Al-Si foundry alloys are generally controlled by their microstructures. The present study was performed to determine the influence of erbium (Er) in Al-7Si-0.3Mg alloys on the microstructures and mechanical properties. The evolution of microstructure was studied by thermal analysis and interrupted solidification technique. Optical microscopy, scanning electron microscope, and energy-dispersive X-ray were employed to characterize the alloy microstructures. The results demonstrated that the addition of Er significantly refined both the secondary dendrite arm spacing (SDAS) and the primary α-Al grain. Simultaneously, Er modified eutectic Si phase from coarse acicular plate-like structures into fine fibrous features. We observed that Er additions strongly suppress the nucleation of eutectic Si due to the preferential formation of ErP instead of AlP. Er additions change the eutectic growth mode from nucleation and growth on AlP particles to the propagation of a defined eutectic front from the mold walls. Moreover, Er addition that was cast for different holding times indicated that there was no fading effect on the SDAS, primary α-Al grain size, and eutectic Si morphology. Importantly, the tensile properties of the Er-modified alloys at as-cast and T6 conditions can be enhanced due to simultaneous refinement both the SDAS and the α-Al grains and modification of the eutectic Si. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect