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加入含有不溶颗粒(硼化物或碳化物)的细化中间合金。这会产生大量的晶粒细化，但不一定影响共晶颗粒或内部枝晶结构的分布。在某些合金组中，例如易加工或回收合金，这些二次颗粒(软或硬/脆颗粒)的尺寸分布和形态以及颗粒内部的树枝状结构至关重要，目前除非使用特殊的外部物理场(电磁、机械或超声波)，否则无法很好地控制这些结构。此外，易加工铝合金目前依赖于铅的添加，由于环境和健康要求，需要逐步淘汰这些添加。因此，寻找化学方法来生产高质量的易加工和/或回收合金是及时和必要的，这些合金具有有利的软、硬相颗粒的尺寸、形态和空间分布。

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.