Synergetic Effect of Surface-active Metallic Additions on Structure Modification in Aluminium Alloys

目前控制变形铝合金组织的主要方法是添加含有不溶性颗粒（硼化物或碳化物）的晶粒细化母合金。这产生了大量的晶粒细化，但不一定影响共晶颗粒的分布或内部枝晶结构。在某些合金中，例如自由加工或回收合金，这些二次颗粒（软或硬/脆颗粒）的尺寸分布和形态以及晶粒的内部枝晶结构是至关重要的，除非使用特殊的外部物理场（电磁，机械或超声波），否则目前无法很好地控制。此外，自由加工铝合金目前依赖于铅的添加，由于环境和健康要求，这种添加需要逐步淘汰。因此，寻找一种化学方法来生产具有良好尺寸、形态和软、硬相颗粒空间分布的可自由加工和/或可回收的高质量合金是及时和必要的。

Main current means to control structure in wrought Al alloys is by adding grain-refining master alloys with insoluble particles (borides or carbides). This produces substantial grain refinement but not necessarily affect the distribution of eutectic particles or internal dendritic structure. In some groups of alloys, e.g. free-machining or recycled alloys, the size distribution and morphology of these secondary particles (soft or hard/brittle particles) as well as the internal dendritic structure of grains are of paramount importance and currently not well controlled unless special external physical fields (electromagnetic, mechanical or ultrasonic) are used. In addition, free-machining aluminium alloys rely currently on additions of Pb that need to be phased out due to the environmental and health requirements. Hence the search for the chemical means to produce good -quality free-machining and/or recycled alloys with beneficial size, morphology and spatial distribution of soft and hard phase particles is timely and necessary.