|About this Abstract
||2019 TMS Annual Meeting & Exhibition
||Solidification Processing of Light Metals and Alloys: An MPMD Symposium in Honor of David StJohn
||Mechanisms of Primary Intermetallic Refinement by Ultrasonic Processing
||Dmitry G. Eskin, Feng Wang, Iakovos Tzanakis, Jiawei Mi
|On-Site Speaker (Planned)
||Dmitry G. Eskin
Primary phases can be beneficial or harmful for aluminum alloys, depending on their morphology, dimensions and amount. Fine and uniformly distributed particles may benefit the mechanical properties, wear resistance and structure refinement. In has been demonstrated that one of the efficient ways of refining the primary crystals like Si, Al3Ti, Al3Zr is ultrasonic processing of the melt. In a series of dedicated experiments using controlled solidification as well as advanced in-situ (synchrotron radiography and tomography, high-speed imaging) and ex-situ (scanning and transmission electron microscopy) structure analysis we have managed to define the mechanisms of primary crystal refinement upon ultrasonic processing as (a) enhanced nucleation on indigenous oxides and (b) fragmentation. As a result the primary crystals are refined and may act as solidification sites for the aluminum phase. This knowledge helps in selecting the temperature ranges of efficient ultrasonic processing.