Higher performance aluminum pressure die-cast alloys through refining

到目前为止，铝压力铸造的合金和工艺发展的特点是铸造性能好，强度高，延展性好。到目前为止，精炼的压力铸造合金很少受到关注，因为精炼的目的是精炼硅沉淀，与砂型和金属型铸造相比，由于冷却速度快，在压力铸造中硅沉淀已经非常细小。然而，新的挑战，特别是由于电子机动性，现在也使部件的导热和导电性成为关注的焦点。该方案的目的是系统地研究用锶精炼常规压铸合金(AlSi9Cu3(Fe)、AlSi10MgMn和AlSi12Cu1(Fe))的效果，并专门用它来显著(&gt；20%)提高铝压铸件的导电性，而不影响其他性能。细化的目的是将通常板状、致密的硅沉淀转变为与基质互穿的结构，以便显著降低它们的高电阻和热阻。适用于细化的后续热处理应进一步增加这一效应，并通过形成沉淀和相应减少基质中固溶体硬化剂的含量来帮助提高导电性。此外，还将了解压铸部件内的导电性如何发展，特别是作为合金成分和工艺参数的函数的铸造壁厚度的函数。基于这些发现，最终将有针对性地选择合适的精炼含量、工艺策略和热处理策略来提高压力压铸件的导电性。

Alloy and process development for aluminum pressure die-casting has until now been characterized by good castability and high strength coupled with good ductility. Refined pressure die-casting alloys have so far received little attention, since the aim of refinement is to refine the silicon precipitations, which in contrast to sand and permanent mold casting are already very fine in pressure die-casting due to the high cooling rates. However, new challenges, in particular due to electro-mobility, are now also bringing the thermal and electrical conductivity of the components into focus. The aim of this proposal is to systematically research the effect of refining conventional pressure die-cast alloys (AlSi9Cu3(Fe), AlSi10MgMn and AlSi12Cu1(Fe)) with strontium and finally to use it specifically to significantly (> 20%) improve the conductivity of aluminum die-cast components without affecting other properties. The aim of the refinement is to convert the normally plate-shaped, compact Si precipitations into interpenetrating structures with the matrix in order to considerably reduce their high electrical and thermal resistance. Subsequent heat treatments adapted to the refinement should further increase this effect and also help to increase the conductivity through the formation of precipitations and the associated reduction in the content of solid solution hardeners in the matrix. Furthermore, an understanding of how the conductivity develops within a die-cast component and in particular as a function of the cast wall thickness as a function of the alloy composition and the process parameters will be developed. Based on these findings, a targeted selection of suitable refinement contents, process strategies and heat treatment strategies to increase the conductivity of pressure die-cast components will ultimately be derived.