Heterogeneous Nb-Based Nuclei for the Grain Refinement of Al-Si Alloys
Heterogeneous Nb-Based Nuclei for the Grain Refinement of Al-Si Alloys
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DOI：
10.1007/s11837-016-1855-8
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发表时间：
2016-04
期刊：
影响因子：
2.6
通讯作者：
L. Bolzoni;N. Hari Babu
中科院分区：
文献类型：
--
作者：
L. Bolzoni;N. Hari Babu
Nb基金属间化合物通常是用于结构应用或低温超导体的低密度高温材料。在这项工作中，我们报道了Al(96)-Nb(2)-B(2)中间合金的发展，其中原位形成的微米级Nb基金属间化合物(即NbB2和Al3Nb)用于完全不同的目的：利用增强的异质形核促进Al-Si合金的细化。Nb基金属间化合物具有密度低、高温稳定性好、晶格匹配性好等特点，适合作为异质形核衬底。结果表明，这些Nb基金属间化合物的加入使所研究的Al-Si合金的显微组织特征得到显著改善。强化的异质形核使材料的晶粒度对冷却速度的依赖程度大大降低，这是影响合金性能变化的关键参数之一。
Nb-based intermetallics are, generally, low-density high-temperature materials used for structural applications or cryogenic superconductors. In this work, we report the development of an Al(96)-Nb(2)-B(2) master alloy where in situ-formed micrometric Nb-based intermetallics (i.e. NbB2and Al3Nb) are used for a completely different purpose: to promote the refinement of Al-Si alloys by taking advantage of enhanced heterogeneous nucleation. Nb-based intermetallics have the right characteristics, like low density, stability at high temperature and good lattice match, to be used as heterogeneous nucleation substrates. It was found that the addition of these Nb-based intermetallics permits the significant refinement of the microstructural features of the Al-Si alloy studied. The enhanced heterogeneous nucleation makes the grain size of the material far less dependent on the cooling rate, which is one of the critical parameters influencing the variation of the properties of the alloy.