Effects of Fe and Ni on the Microstructure and High Temperature Tensile Properties of Al-Si Aluminium Alloys

Abstract

The effects of varied contents of Ni (1.2 wt.%, 1.6 wt.%) and Fe (0.6 wt.%, 0.8 wt.%) on the microstructure and high temperature mechanical properties of Al-Si alloy were studied using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and tensile testing machine. The experimental results demonstrate that Ni element plays a crucial role in modifying the Fe-rich phase type, morphology and distribution in the Al-Si alloy. The addition of 1.2 wt.% Ni and 0.6 wt.% Fe could generate a Chinese script Fe-rich strengthening phase in Al-Si alloy. Further increasing to 1.6 wt.% Ni and 0.8 wt.% Fe, the long needle-shape Fe-rich phase was detected. High temperature tensile properties of the alloy were significantly improved, because of the Chinese script Fe-rich strengthening phase in the Al-Si alloy containing 1.2 wt.% Ni and 0.6 wt.% Fe. The ultimate tensile strength (UTS) of Al-Si alloy with 1.2 wt.%Ni-0.6 wt.% Fe is up to 229 MPa, 174 MPa and 139 MPa at 250 °C, 300 °C and 350 °C, respectively.