Phase-field simulation of solidification dendritic segregation in Ti-45Al alloy
| Autor: | Yun Chi, Chun-qing Hu, Yu-tuo Zhang |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Work (thermodynamics)
Morphology (linguistics) Materials science Alloy Regular solution Thermodynamics 02 engineering and technology engineering.material lcsh:Technology 01 natural sciences phase-field model dendritic segregation Ti-45Al free energy isothermal solidification Dendrite (crystal) lcsh:Manufactures Phase (matter) 0103 physical sciences Materials Chemistry Tip growth 010302 applied physics lcsh:T Metallurgy Metals and Alloys 021001 nanoscience & nanotechnology Microstructure engineering 0210 nano-technology lcsh:TS1-2301 |
| Zdroj: | China Foundry, Vol 14, Iss 3, Pp 184-187 (2017) |
| ISSN: | 2365-9459 1672-6421 |
| DOI: | 10.1007/s41230-017-6127-x |
| Popis: | The microstructures and mechanical properties of TiAl alloys are directly linked to micro-segregation which cannot be avoided during solidification. So a thorough understanding of the micro-segregation should be a great help to further enhance the mechanical properties of the cast products. Theoretical analysis and experiments have been used to predict the micro-segregation, but it is very difficult to observe and determine the dendritic segregation in the micro region. Phase-field method has been employed for the simulation of dendritic growth. However, due to the complicated quasi-sub regular solution model for Ti-45Al(at.%) alloy, the classic phase-field models have difficulty to deal with the free energy. In this work, a phase-field model by linking thermodynamic calculation was used to simulate solidification dendritic segregation of Ti-45Al alloy for Liquid→Liquid+β(Ti). The free energies of solid phase and liquid phase for Ti-45Al alloy were calculated by Thermo-Calc and then coupled with the phase-field equations. The simulation results show the dendritic morphology and Al content variations between liquid and growing solid phase for Ti-45Al alloy. With the growth of the β(Ti), dendritic segregation is formed in the liquid and solid phases due to the solute partitioning and rejection into the liquid. As a result, the dendrite arms are depleted of Al element, while the inter-dendrites are enriched. The dendritic tip growth velocity decreases with the progress of solidification, whereas the segregation ratio increases. |
| Databáze: | OpenAIRE |
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