Abstract
Characterization of porosity formation in an A356 alloy with different oxide levels during directional solidification was investigated using micro-focus X-ray imaging and directional solidification technology. Stirring melt is thought to provide more active nucleation sites for pore formation, thus lead to a remarkable rise in the nucleation temperature of pores. The fast growth of those pores formed at higher temperatures further restrains the succeeding nucleation operations in local regions, and results in a considerable reduction in the pore volume density but a significant increases in pore volume fraction. Fluctuations of pore volume fraction and pore volume density along solidification length is thought to be closely related to a competition mechanism of pore nucleation with pore growth for hydrogen supplement. The increase in oxide content by stirring melt completely changes the pore size distribution and considerably increases the average size of pores formed.
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Liao, H., Song, W., Wang, Q. (2013). Characterization of Pore Formation in A356 Alloy with Different Oxide Levels During Directional Solidification. In: Zhang, L., Allanore, A., Wang, C., Yurko, J.A., Crapps, J. (eds) Materials Processing Fundamentals. Springer, Cham. https://doi.org/10.1007/978-3-319-48197-5_19
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DOI: https://doi.org/10.1007/978-3-319-48197-5_19
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