Abstract This work demonstrates two phenomena both grain refinement and the proportion of twin boundaries increase from 0.3% for a randomly oriented regular FCC grain to 2.36% in equiaxial solidified Al-0.2wt%Ti alloy. Five adjacent grains exhibiting twin relationships share the common 〈1 1 0〉 direction and demonstrate a fivefold symmetry axis. This special symmetry relationship gives a new light on twin grain nucleation. An abundant icosahedron in the melting is constituted of twenty regular tetrahedrons. Thus, icosahedral quasicrystal would play a role of bridge between icosahedral cluster and crystal nucleus to significantly promote nucleation.

中文翻译：

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添加 Ti 精炼剂在商业纯铝中形成孪晶界

摘要 这项工作证明了晶粒细化和孪晶界比例从随机取向规则 FCC 晶粒的 0.3% 增加到等轴凝固 Al-0.2wt%Ti 合金的 2.36% 的两种现象。表现出孪生关系的五个相邻晶粒共享共同的<1 1 0> 方向并表现出五重对称轴。这种特殊的对称关系为双晶成核提供了新的线索。熔化中的一个丰富的二十面体由二十个正四面体构成。因此，二十面体准晶将在二十面体簇和晶核之间起桥梁作用，显着促进成核。