Basic investigations of the preparation and properties of in-situ Al3Ti reinforced aluminium cast alloys

限制铝铸件使用的往往不是其强度，而是合金的刚度。因此，本项目的目的是通过原位形成非常坚硬的金属间相Al3Ti来显著增加铝铸造合金的刚度。由于钛在铝熔体中的低溶解度，这通过常规熔体冶金是不可能的。为了制备微米级的Al_3Ti颗粒，采用了Ti粉颗粒（约50 μm）与铝液原位反应制备Al_3Ti，并结合了一种新型的高剪切装置。与钛向Al3Ti的转化相关的体积的显著增加以及由此产生的高应力预计将导致Al3Ti相非常精细地破碎成微米尺寸的颗粒。由于剪切单元施加的高剪切力，这些颗粒将从初始钛相分离并有效地分布在熔体内。对铸造铝合金中原位增强相的形成动力学及其增强效果进行了初步分析。研究了典型压铸合金元素Si、Mg对合金性能的影响。基于这些知识，最终的目标是设计一种原位增强铝合金，其刚度大大超过商业压铸合金。

Limiting for the use of aluminum castings is often not their strength, but the stiffness of the alloy. The aim of this project is therefore to increase significantly the stiffness of aluminum casting alloys by in situ formation of the very stiff intermetallic phase Al3Ti. Due to the low solubility of titanium in the aluminum melt, this is not possible by conventional melt metallurgy. In order to generate micrometer sized Al3Ti particles, an in-situ reaction of Ti powder particles (about 50 μm) with liquid aluminum to Al3Ti combined with a novel high-shear unit is used. The significant increase in volume associated with the conversion of titanium to Al3Ti and the resulting high stresses are expected to lead to a very fine fragmentation of the Al3Ti phase into micrometer-sized particles. These particles will be detached from the initial titanium phase and effectively distributed within the melt due to the high shear forces applied by the shear unit. The formation kinetics of the in-situ reinforcement phase and its reinforcement effect in aluminum cast alloys is fundamentally analyzed. The influence of typical die casting alloying elements such as Si and Mg is investigated. Based on this knowledge, the ultimate aim is to design an in-situ reinforced aluminum alloy whose stiffness exceeds significantly that of commercial die casting alloys.