Containerless solidification of undercooled NdFeZrB alloy droplets in a drop tube
Containerless solidification of undercooled NdFeZrB alloy droplets in a drop tube
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过冷 NdFeZrB 合金液滴在滴管中的无容器凝固
DOI：
10.1016/s0925-8388(98)00870-6
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发表时间：
1999
影响因子：
6.2
通讯作者：
B. Wei
中科院分区：
文献类型：
--
作者：
Jianrong Gao;B. Wei
利用3 m落管对Nd13Fe79.9Zr0.1B7合金过冷液滴的无容器凝固过程进行了研究。结果表明，液滴的凝固机制与其尺寸密切相关。由于小的过冷度和高的冷却速率，大的液滴（≥300 μm）通过不完全的包埋反应凝固，从而导致大量保留的初生铁枝晶。但由于过冷度的增加，大部分小液滴（<300 μm）通过Nd2Fe14B相的初晶化而凝固。结果，形成由粗大的树枝状Nd2Fe14B晶粒组成的显微组织。因此，有人建议，大的过冷凝固前是能够避免形成初级游离铁在近化学计量比的NdFeB合金，从而提供了一个有前途的方式来制备母合金的制造具有增强的能量产品的磁体。
Containerless solidification of undercooled Nd13Fe79.9Zr0.1B7alloy droplets was investigated using a 3-m drop tube. It was found that the solidification mechanism of droplets depends strongly on their sizes. Due to small undercoolings and high cooling rates, large droplets (≥300 μm) are solidified via an incomplete peritectic reaction, thus leading to a large amount of preserved primary iron dendrites. However, most of small droplets (<300 μm) are solidified by the primary crystallization of Nd2Fe14B phase owing to enhanced undercooling levels. As a result, a microstructure consisting of coarse dendritic Nd2Fe14B grains is formed. It was therefore suggested that large undercooling prior to solidification is able to avoid the formation of primary free iron in near-stoichiometric NdFeB alloys, thus providing a promising way to prepare master alloys for the fabrication of magnets with enhanced energy products.