Mechanisms of nucleation and defect growth in undercooled melt containing oxide clusters
Mechanisms of nucleation and defect growth in undercooled melt containing oxide clusters
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DOI：
10.1016/j.actamat.2023.118942
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发表时间：
2023-04
期刊：
影响因子：
9.4
通讯作者：
Sepideh Kavousi;M. A. Zaeem
中科院分区：
文献类型：
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作者：
Sepideh Kavousi;M. A. Zaeem
采用分子动力学模拟方法研究了氧化物团簇存在下过冷铝凝固过程中的形核和缺陷生长机制。在不作为异质成核位点或改变整体平均晶粒尺寸的情况下，Al氧化物（Al 2 O3）诱导远离氧化物表面的纳米结构的局部变化。基于平台-台阶模型的凝固热力学模拟表明，液态Al-固态Al 2 O3界面的非润湿性质阻止了氧化物表面上完美和孪晶结构的形成。延迟晶体成核和稳态凝固，然后由较小的晶粒急剧增长被确定为触发晶体取向选择的变化，并增加氧化物表面之间的区域中的孪晶结构的局部分数。最后，我们的调查生长孪晶界的形成提供了第一个计算证据，这两个逐层添加和形成分解的晶界机制支配的五倍孪晶界在Al的凝固过程中的形成。
Mechanisms governing the nucleation and defect growth during solidification of undercooled aluminum (Al) in the presence of oxide clusters are studied by molecular dynamics (MD) simulations. Without serving as heterogeneous nucleation sites or changing the overall average grain size, Al oxides (Al2O3) induce localized variations in nanostructures away from the oxide surfaces. Thermodynamic modeling of solidification based on the terrace-ledge model suggests that the non-wetting nature of the liquid Al- solid Al2O3interface prevents formation of perfect and twinned structures on oxide surfaces. Delayed crystal nucleation and steady-state solidification followed by a sharp growth of smaller grains are identified to trigger variations in crystal orientation selection and increase the localized fraction of twinned structures in regions between oxide surfaces. Finally, our investigation of formation of growth twin boundaries provides the first computational evidence that both layer-by-layer additions and formation-decomposition of grain boundaries mechanisms govern the formation of five-fold twin boundaries during solidification of Al.