Solidification orientation relationships between Al3Ti and TiB2
Solidification orientation relationships between Al3Ti and TiB2
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DOI：
10.1016/j.actamat.2019.12.013
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发表时间：
2020-03
期刊：
影响因子：
9.4
通讯作者：
Y. Cui;D. King;A. Horsfield;C. Gourlay
中科院分区：
文献类型：
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作者：
Y. Cui;D. King;A. Horsfield;C. Gourlay
取向关系（OR）可以在固化过程中通过各种机制形成，这些机制在固化后通常难以区分。在这里，我们研究了由Al 3 Ti在TiB 2上的形核以及在过包晶富Al熔体中生长Al 3 Ti小平面对TiB 2的推动和吞没形成的三个OR。通过生长相对大的TiB 2晶体，在TiB 2的一个（0001）面上固化多个小的Al 3 Ti晶体，并通过电子背散射衍射（EBSD）测量所得的OR来识别成核OR。通过EBSD测量数据的统计分析、界面能的密度泛函理论（DFT）计算以及TiB 2颗粒被Al 3 Ti小面挤压和吞没截面的成像，研究了挤压和吞没OR。结果表明，最低的能量OR是由成核以及通过推/吞没。较高的能量OR，形成的推动和吞没，对应于当地的界面能最小值，可以解释由旋转的TiB 2颗粒在Al 3 Ti方面在推动。
Orientation relationships (ORs) can form during solidification by a variety of mechanisms that are often difficult to distinguish after solidification. Here we study three ORs formed by the nucleation of Al3Ti on TiB2, and by the pushing and engulfment of TiB2by growing Al3Ti facets in hyperperitectic Al-rich melts. The nucleation OR is identified by growing a relatively large TiB2crystal, solidifying multiple small Al3Ti crystals on one (0001) facet of TiB2, and measuring the resulting OR by electron backscatter diffraction (EBSD). Pushing and engulfment ORs are investigated by statistical analysis of EBSD measurements, density functional theory (DFT) calculations of interface energies, and imaging of cross-sections of TiB2particles being pushed and engulfed by Al3Ti facets. It is shown that the lowest energy OR is formed by nucleation as well as by pushing/engulfment. The higher energy ORs, formed by pushing and engulfment, correspond to local interfacial energy minima and can be explained by rotation of TiB2particles on Al3Ti facets during pushing.