The impact of small Zr addition to Al–Ni cast alloy for elevated temperature applications

Most aluminium casting alloys are based on the eutectic system Al–Si, which has weak thermal properties. Alloys from the eutectic Al–Ni system on the other hand have higher thermal stability and good casting properties and are therefore promising for casting applications. Using casting simulations, a copper mold was designed to achieve cooling rates above 100 K/s with the aim of producing a Zr-rich supersaturated solid solution. Microstructural analysis revealed that the addition of Zr leads to notable changes in the microstructure characterised by the formation of primary Al 3 Zr and α Al dendrites. Subsequent heat treatment revealed that Zr-enriched alloys undergo significant age hardening, which showed an improvement in microhardness due to effective Al 3 Zr precipitation.