In-situ reinforcement of Aluminium casting alloys
Description / Outline
The development of Aluminum alloys mainly tends to increase the strength without worsening the ductility. Beside strength an increase in stiffness is also sought. In contrast to strength with Aluminium casting alloys the stiffness can be influenced by alloying to a very small extent only. A substantial increase in stiffness is possible by metal matrix composits. But poor wettability between the metal matrix and the ceramic particels and big differences in the thermal expansion lead to poor mechanical properties. One possible approach to solve these problems is using intermetallics based on Aluminium as reinforcement. These phases have a low density and a good wettability with the Aluminium matrix. Moreover, these phases can be produced by an in-situ reaction in the aluminum melt. The volume fraction of the reinforcing phase increases with this reaction. A special stirring technique ensures that the reinforcing phase is finely divided and the matrix solidifies fine-grained.