Mechanism of anomalous eutectic formation in the solidification of undercooled Ni–Sn eutectic alloy
Mechanism of anomalous eutectic formation in the solidification of undercooled Ni–Sn eutectic alloy
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DOI：
10.1557/jmr.2008.0259
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发表时间：
2008-08
影响因子：
2.7
通讯作者：
J. F. Li;X. Li;L. Liu;S. Lu
中科院分区：
文献类型：
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作者：
J. F. Li;X. Li;L. Liu;S. Lu
用光学金相和电子背散射衍射法研究了过冷Ni-18.7at.%Sn共晶合金凝固组织中的反常共晶组织。结果表明，在所研究的过冷度范围内，α-Ni颗粒在反常共晶中基本上是随机分布的。另一种共晶相β-Ni3SN在低过冷度时取向良好，但随着过冷度的增加，取向逐渐不一致，晶界数目增多。当凝固组织由异常共晶+片状共晶转变为超过130K临界过冷度的完全异常共晶时，β-Ni3Sn相的取向偏差从测量区完全消失。初步认为初生固相部分重熔是反常共晶形成的原因，并进行了定量分析。
Anomalous eutectics in the solidification structure of undercooled Ni–18.7 at.% Sn eutectic alloy were examined by optical metallography and electron backscattered diffraction. It was revealed that α–Ni particulates are, in principle, randomly distributed in the anomalous eutectics in the undercooling range investigated. Another eutectic phase, β–Ni_3Sn, is well orientated at low undercoolings but gradually becomes inconsistent in orientation as undercooling increases, accompanied by an increasing number of grain boundaries in it. As the solidification structure changes from a mixture of anomalous eutectics plus lamellar eutectics to full anomalous eutectics beyond a critical undercooling of 130 K, however, misorientation in the β–Ni_3Sn phase disappears completely from the measurement area. Partial remelting of the primary solid was proposed to be the origin of the anomalous eutectic formation, and quantitative analyses were performed.