Solidification of tetragonal Ni2B from the undercooled melt
Solidification of tetragonal Ni2B from the undercooled melt
复制标题
DOI：
10.1209/0295-5075/97/36003
复制
发表时间：
2012-02
期刊：
影响因子：
--
通讯作者：
S. Binder;M. Kolbe;S. Klein;D. Herlach
中科院分区：
文献类型：
--
作者：
S. Binder;M. Kolbe;S. Klein;D. Herlach
测量了四方Ni2B晶体非平衡凝固过程中枝晶生长速度随电悬浮液滴过冷度的变化规律。采用高速视频成像技术，对样品表面的固液界面传播进行了原位测量。为了分析原始数据，建立了一个三维模型来确定熔体体积内的生长速度。通过微观结构分析，揭示了四方Ni2B晶体与立方晶体明显不同的晶型形成机制。枝晶尖端垂直于结晶学{111}面生长。因此，凝固前沿在宏观尺度上的传播由四方晶体结构的晶格参数决定。在细观尺度下，采用尖界面模型分析了枝晶沿{111}法线方向的生长速度。
The dendrite growth velocity during non-equilibrium solidification of tetragonal Ni2B crystals is measured as a function of undercooling on electrostatically levitated droplets. High-speed video imaging is applied to measure in situ the propagation of the solid-liquid interface apparent on the sample surface. To analyze the raw data, a three-dimensional model is developed to determine the growth velocity within the volume of the melt. Microstructure analysis is performed to resolve the pattern formation mechanism of tetragonal Ni2B crystals which differs significantly from the cubic case. The dendrite tips are found to grow perpendicular to the crystallographic {111} planes. As a consequence, the propagation of the solidification front on a macroscopic scale is determined by the lattice parameters of the tetragonal crystal structure. The dendrite growth velocities along the {111} normal directions are analyzed on a mesoscopic scale within a sharp-interface model.