The Synergistic Refinement and Modification of Al-7Si Alloys Caused by Trace Er and B
In this investigation, it was found that the co-addition of Er and B causes both the modification and refinement of the Al-7Si alloy. The B element mainly forms a small amount of the AlB2 phase within the alloy, which can be used as a nucleation site for grains during casting, so the addition of B c...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-04-01
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| Series: | Metals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-4701/15/4/413 |
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| Summary: | In this investigation, it was found that the co-addition of Er and B causes both the modification and refinement of the Al-7Si alloy. The B element mainly forms a small amount of the AlB2 phase within the alloy, which can be used as a nucleation site for grains during casting, so the addition of B can significantly reduce the grain size of the Al-7Si alloy. However, the number density of AlB2 phase is too low, so its effect on improving the eutectic Si size and reducing the secondary dendrite arm spacing (SDAS) is not significant. The addition of 0.1 wt% Er can form a large amount of Al3Er phase within the alloy, which mainly serves as a nucleation site for eutectic Si during casting, so the addition of Er can significantly reduce the SDAS, eutectic Si size and morphology of Al-7Si alloys. However, due to the existence of a certain degree of mismatch between the Al matrix and the Al3Er phase, the relative grain refinement effect of Al3Er is not significant. In addition to this, we also observe the enrichment of Er at eutectic Si, which suggests that Er can interact with Si and thus inhibit the growth of eutectic Si. Therefore, Er can modulate eutectic Si through the Al3Er phase and the enrichment of Er. The co-addition of Er and B to Al-7Si alloys has better refining and modification effects than the addition of Er or B alone, mainly due to the modification effect of the Er element and the refining effect of the AlB2 phase. Unlike the Er-containing alloys, where the Al3Er phase plays a modifying role, the modification of the co-addition Er and B alloys is mainly caused by the enrichment of Er within the alloy. |
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| ISSN: | 2075-4701 |