Balasubramani Nagasivamuni, StJohn David, Dargusch Matthew, Wang Gui
Centre for Advanced Material Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, The University of Queensland, St Lucia 4072, Australia.
DMTC Limited, The University of Queensland, St Lucia 4072, Australia.
Materials (Basel). 2019 Sep 28;12(19):3187. doi: 10.3390/ma12193187.
Research on ultrasonic treatment (UST) of aluminium, magnesium and zinc undertaken by the authors and their collaborators was stimulated by renewed interest internationally in this technology and the establishment of the ExoMet program of which The University of Queensland (UQ) was a partner. The direction for our research was driven by a desire to understand the UST parameters that need to be controlled to achieve a fine equiaxed grain structure throughout a casting. Previous work highlighted that increasing the growth restriction factor can lead to significant refinement when UST is applied. We extended this approach to using the Interdependence model as a framework for identifying some of the factors (e.g., solute and temperature gradient) that could be optimised in order to achieve the best refinement from UST for a range of alloy compositions. This work confirmed established knowledge on the benefits of both liquid-only treatment and the additional refinement when UST is applied during the nucleation stage of solidification. The importance of acoustic streaming, treatment time and settling of grains were revealed as critical factors in achieving a fully equiaxed structure. The Interdependence model also explained the limit to refinement obtained when nanoparticle composites are treated. This overview presents the key results and mechanisms arising from our research and considers directions for future research.
作者及其合作者对铝、镁和锌进行超声处理（UST）的研究，是受到国际上对该技术重新产生的兴趣以及“ExoMet计划”的设立所推动，昆士兰大学（UQ）是该计划的合作伙伴之一。我们的研究方向是由这样一种愿望驱动的，即了解为在整个铸件中获得精细等轴晶粒结构而需要控制的UST参数。先前的工作强调，当应用UST时，增加生长限制因子可导致显著细化。我们将这种方法扩展到使用相互依存模型作为一个框架，以识别一些可以优化的因素（例如溶质和温度梯度），以便在一系列合金成分中通过UST实现最佳细化。这项工作证实了关于仅进行液体处理的益处以及在凝固形核阶段应用UST时额外细化效果的既有知识。声流、处理时间和晶粒沉降的重要性被揭示为实现完全等轴结构的关键因素。相互依存模型还解释了处理纳米颗粒复合材料时获得的细化极限。本综述介绍了我们研究产生的关键结果和机制，并考虑了未来研究的方向。
