关于Sn-Ni包晶合金定向凝固中断过程中初生/包晶界面的迁移

On migration of primary/peritectic interface during interrupted directional solidification of Sn-Ni peritectic alloy.

作者信息

Peng Peng, Li Xinzhong, Li Jiangong, Su Yanqing, Guo Jingjie, Fu Hengzhi

机构信息

Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, China.

MOE Key Laboratory for Magnetism and Magnetic Materials, Lanzhou University, Lanzhou 730000, China.

出版信息

Sci Rep. 2016 Apr 14;6:24512. doi: 10.1038/srep24512.

DOI:10.1038/srep24512

PMID:27075006

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4830927/

Abstract

The migration of the primary/peritectic interface in local isothermal condition is observed in dendritic structure of Sn-Ni peritectic alloy after experiencing interrupted directional solidification. It was observed that this migration of primary Ni3Sn2/peritectic Ni3Sn4 interface towards the primary Ni3Sn2 phase was accompanied by migration of liquid film located at this interface. The migration velocity of this interface was confirmed to be much faster than that of peritectic transformation, so this migration was mostly caused by superheating of primary Ni3Sn2 phase below TP, leading to nucleation and migration of liquid film at this interface. This migration can be classified as a kind of liquid film migration (LFM), and the migration velocity at the horizontal direction has been confirmed to be much faster than that along the direction of temperature gradient. Analytical prediction has shown that the migration of liquid film could be divided into two stages depending on whether primary phase exists below TP. If the isothermal annealing time is not long enough, both the liquid film and the primary/peritectic interface migrate towards the primary phase until the superheated primary phase has all been dissolved. Then, this migration process towards higher temperature is controlled by temperature gradient zone melting (TGZM).

摘要

在经历间断定向凝固后的Sn-Ni包晶合金枝晶结构中，观察到了局部等温条件下初生/包晶界面的迁移。观察发现，初生Ni3Sn2/包晶Ni3Sn4界面朝着初生Ni3Sn2相的这种迁移伴随着位于该界面处的液膜的迁移。该界面的迁移速度被证实比包晶转变的速度快得多，因此这种迁移主要是由初生Ni3Sn2相在平衡熔点（TP）以下的过热度引起的，导致该界面处液膜的形核和迁移。这种迁移可归类为一种液膜迁移（LFM），并且已证实在水平方向上的迁移速度比沿温度梯度方向的迁移速度快得多。分析预测表明，根据初生相在平衡熔点（TP）以下是否存在，液膜的迁移可分为两个阶段。如果等温退火时间不够长，液膜和初生/包晶界面都会朝着初生相迁移，直到过热的初生相全部溶解。然后，这种向更高温度的迁移过程由温度梯度区域熔化（TGZM）控制。