Reactive synthesis of hexagonal Ti5P3.16 crystals and their heterogenous nucleating mechanism on primary Si
Reactive synthesis of hexagonal Ti5P3.16 crystals and their heterogenous nucleating mechanism on primary Si
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六方Ti 5 P 3.16 晶体的反应合成及其在初晶硅上的异相成核机制
DOI：
10.1016/j.jallcom.2018.09.038
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发表时间：
2019-03-10
影响因子：
6.2
通讯作者：
Liu, Xiangfa
中科院分区：
文献类型：
--
作者：
Nie, Jinfeng;Zhao, Yonghao;Liu, Xiangfa
首次在Al-Ti-P-C合金中研究了Ti5P3.16晶体的反应合成，并揭示了Ti5P3.16晶体对Al-Si合金中原生硅的有效细化。结果表明，Al熔体中P原子与TiC粒子直接反应形成Ti5P3.16相。在反应过程中，P原子吸附在TiC团聚体上，引发逐渐的相分解，随后释放出来的Ti原子与周围的P原子结合形成Ti-P相。TEM和SEM表征表明，Ti5P3.16相具有六角形密排晶格结构，主要表现为由6个{10-10}面和2个平行{0001}面包围的规则六角形棱镜形态。此外，含有Ti5P3.16颗粒的Al-Ti-P-C合金对过共晶Al-Si合金的初生Si颗粒具有有效的细化性能，A390合金的初生Si颗粒的平均尺寸从85 μ m减小到12.5 μ m。为了揭示细化机理，研究了Al-Si熔体中Si原子诱导Ti5P3.16相的演化过程，表明Ti5P3.16加入Al-Si熔体后转变为大量尺寸约为100-200 nm的纳米AlP颗粒。随着熔体温度的降低，这些具有新鲜界面的原位AlP颗粒均匀分布在熔体中，并在Al-Si熔体的后续凝固过程中充当初生Si的有效异质核，导致A390合金组织的显著细化。(C) 2018年Elsevier B.V.出版
Reactive synthesis of Ti5P3.16 crystals was firstly investigated in the Al-Ti-P-C alloy and their effective refinement on primary Si in Al-Si alloys was also revealed. It was found that the Ti5P3.16 phase was formed by the direct reaction of P atoms with TiC particles in Al melt. During the reaction process, P atoms absorbed on TiC agglomerates and initiated the gradual phase decomposition, and then the releasing Ti atoms combined surrounding P ones together to form Ti-P phase. Based on the TEM and SEM characterization, it is identified that the Ti5P3.16 phase has an hexagonal close packed crystal lattice structure and mainly displays a regular hexagonal prism morphology enclosed by six {10-10} facets and two parallel {0001} ones. Furthermore, the Al-Ti-P-C alloy containing the Ti5P3.16 particles showed an efficient refinement performance on primary Si particles for hypereutectic Al-Si alloy, whose average size was reduced from 85 mu m to 12.5 mu m for A390 alloy. In order to reveal the refinement mechanism, the evolution process of the Ti5P3.16 phase induced by Si atoms in the Al-Si melt was carried out, indicating that the Ti5P3.16 transformed into amounts of nano AlP particles with sizes of about 100-200 nm after added into the melt. Then, these in-situ AlP particles with fresh interfaces distributed uniformly in the melt and act as the effective heterogenous nuclei for the primary Si during the following solidification process of Al-Si melt with the decrease of the melt temperature, which leads to significantly refinement of the microstructure of A390 alloys. (C) 2018 Published by Elsevier B.V.