A refining mechanism of primary Al₃Ti intermetallic particles by ultrasonic treatment in the liquid state

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• 作者：Feng Wang^a ; ^{feng.wang@brunel.ac.uk" class="auth_mail" title="E-mail the corresponding author} ; Dmitry Eskin^a ; ^b ; Jiawei Mi^c ; Thomas Connolley^d ; John Lindsay^e ; Maher Mounib^f
• 关键词：Aluminium alloys ; Ultrasonic treatment ; Primary intermetallic ; Aluminium oxide ; Heterogeneous nucleation
• 刊名：Acta Materialia
• 出版年：2016
• 出版时间：1 September 2016
• 年：2016
• 卷：116
• 期：Complete
• 页码：354-363
• 全文大小：3970 K

文摘

The mechanism underlying the considerable refinement of primary Al₃Ti intermetallic particles induced by ultrasonic treatment (UST) in an Al-0.4 wt% Ti alloy in the fully liquid state was investigated. Scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam 3D tomography and transmission electron microscopy were used to clearly identify that α-Al₂O₃ particles were located at or near the centres of primary Al₃Ti particles in the samples solidified with and without UST. Crystallographic evaluation using the edge-to-edge matching model and experimental determination of orientation relationships between the α-Al₂O₃ and primary Al₃Ti particles using the convergent beam Kikuchi line diffraction patterns confirmed the high potency of α-Al₂O₃ particles as nucleation sites for the Al₃Ti phase. Based on the experimental results, the refining mechanism is discussed in terms of proposed hypotheses in the literature. It is suggested that the significant refinement of primary Al₃Ti particles upon UST is due to the cavitation-induced deagglomeration and distribution of the α-Al₂O₃ particles and the cavitation-enhanced wetting of the α-Al₂O₃ particles by liquid aluminium.