Abstract 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 TiB2 by growing Al3Ti facets in hyperperitectic Al-rich melts. The nucleation OR is identified by growing a relatively large TiB2 crystal, 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 TiB2 particles 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 TiB2 particles on Al3Ti facets during pushing.

中文翻译：

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Al3Ti和TiB2凝固取向关系

摘要 定向关系 (ORs) 可以在凝固过程中通过多种机制形成，这些机制通常在凝固后难以区分。在这里，我们研究了由 Al3Ti 在 TiB2 上成核形成的三个 OR，以及通过在超包晶富铝熔体中生长 Al3Ti 面推动和吞没 TiB2。通过生长相对较大的 TiB2 晶体，在 TiB2 的一个 (0001) 面上固化多个小的 Al3Ti 晶体，并通过电子背散射衍射 (EBSD) 测量所得的 OR，可以识别成核 OR。通过 EBSD 测量的统计分析、界面能的密度泛函理论 (DFT) 计算以及被 Al3Ti 面推动和吞没的 TiB2 颗粒的横截面成像，对推动和吞没 OR 进行了研究。结果表明，最低能量 OR 是由成核以及推动/吞没形成的。通过推动和吞没形成的较高能量 ORs 对应于局部界面能量最小值，可以通过推动过程中 TiB2 颗粒在 Al3Ti 面上的旋转来解释。