Abstract By using the electron backscattered diffraction (EBSD) technique, pattern selection of twinned growth in Al-4.5 wt% Cu alloy has been studied in Bridgman solidification experiments. Based on the original twin planes formed at 3000 μm/s, the twinned growth was produced till the end of solidification after abruptly decreasing the growth rate to 100, 50, 20, 10, 5, 3, 1 and 0.3 μm/s. The stable twinned growth could be achieved during a wide range of solidification process. For the first time, the so-called twinned cell pattern was observed and prevailed in the solidified structure at 3 and less than 3 μm/s. The twinned growth in aluminum alloy was not limited to dendrite pattern as has previously been reported. The twinned pattern selection map was also revealed. Meanwhile, an interesting orientation rotation phenomenon was elucidated using EBSD technique on both sides of the coherent twin boundary during twinned cell growth. At a lower rate of 0.3 μm/s, the orientation rotation deflection concerning the original Σ3 60° twinning relation was confirmed. Some coincidence site lattice boundaries with higher Σ values served as the preferred states for this orientation deflection during growth.

中文翻译：

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Bridgman凝固过程中铝合金孪晶生长模式的选择

摘要 利用电子背散射衍射(EBSD)技术，在Bridgman凝固实验中研究了Al-4.5 wt% Cu合金孪晶生长模式的选择。在原来的 3000 μm/s 形成孪晶面的基础上，将生长速率突然降低到 100、50、20、10、5、3、1 和 0.3 μm/s 后，产生孪晶生长直到凝固结束。在广泛的凝固过程中可以实现稳定的孪生生长。首次观察到所谓的孪晶胞图案，并在 3 μm/s 和小于 3 μm/s 的凝固组织中占优势。铝合金中的孪生生长不限于先前报道的枝晶图案。孪生模式选择图也被曝光。同时，在孪晶细胞生长过程中，在相干孪晶边界两侧使用 EBSD 技术阐明了一个有趣的取向旋转现象。以 0.3 μm/s 的较低速率，证实了关于原始 Σ3 60°孪晶关系的取向旋转偏转。一些具有较高 Σ 值的重合位点晶格边界作为生长过程中这种取向偏转的首选状态。