Microstructure, hardening and mechanical properties of hypoeutectic Al-Ce-Ni alloys with Zr and Zr+Sc additions and the effect of ultrasonic melt processing

Abstract

Ternary Al-Ce-Ni alloys have a potential in the manufacture of automotive and airspace components, as well as in replacing traditional aluminum alloys in high-temperature applications, which is determined by the formation of fine and thermally stable Al11Ce3 and Al3Ni eutectic. In this study we successfully improved the microstructure and mechanical properties of a hypoeutectic Al4Ce2Ni alloy by using Zr and Zr+Sc additions combined with ultrasonic melt processing and dispersion hardening. As a result, the grain structure of the as-cast alloys was significantly refined and the annealing at 350 °C led to a considerable hardening effect, especially in the alloys with Zr+Sc additions (doubling the hardness). Al3Zr and Al3(Zr,Sc) coherent particles were identified as hardening nano-precipitates. The compressive mechanical testing at room and elevated temperatures showed that the additions of Zr and Zr+Sc improved the strength with the additional increase caused by ultrasonic melt processing.