A pre-melting phenomenon in sodium—potassium alloys
A pre-melting phenomenon in sodium—potassium alloys
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DOI：
10.1080/14786436708221642
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发表时间：
1967
影响因子：
1.6
通讯作者：
D. P. Woodruff;A. J. Forty
中科院分区：
文献类型：
--
作者：
D. P. Woodruff;A. J. Forty
摘要：采用透射紫外显微镜技术对富钾钠钾合金的熔融过程进行了直接观察。用这种方法可以观察到晶界和固体金属中某些其他预定位置的预熔化。在高熔化速率下，在主要推进的熔化锋前面观察到稀释合金和熔融金属条的显微组织。这可以用钠从固体向液相局部扩散引起的不稳定性来解释，这导致了一种“结构性过热”。这与凝固过程中的本构过冷有相似之处，过冷会导致众所周知的固/液界面的细胞结构。然而，与后一种效应不同的是，在本构过热中，不稳定性并不发生在界面附近，而只发生在它前面的固体金属中。这可以解释为如果固体温度…
Abstract A study of melting in potassium-rich sodium-potassium alloys has been made by direct observation using the technique of transmission ultra-violet microscopy. In this way it has been possible to observe pre-melting of grain boundaries and certain other pre-determined sites in the solid metal. At high rates of melting a microstructure of diluted alloy and molten strips of metal is observed ahead of the main advancing melting front. This is explained in terms of an instability arising from the local diffusion of sodium from the solid into the liquid phase, resulting in a form of ‘constitutional superheating'. There is an analogy between this and constitutional supercooling which occurs in solidification and leads to the well-known cellular structure of the solid/liquid interface. However, unlike this latter effect, in constitutional superheating the instability does not occur in the immediate vicinity of the interface but only in the solid metal ahead of it. This can be explained if the solidus temp...