Influence of Fe and Ni micro-alloying on the microstructure and mechanical properties of Al-11 Si aluminum alloys
The study examined the influence of different contents of Ni(1.2 and 1.6wt.%)and Fe(0.6 and 0.8wt.%)on the microstructure and me-chanical properties at different temperature of the Al-11Si aluminum alloy using scanning electron microscopy(SEM),energy dispersive X-ray spec-troscopy(EDS)and tensile testing machine.The experimental results showed that the presence of Ni element positively affected the type,morphology and distribution of the Fe-rich phase in Al-11Si aluminum alloy.The addition of 1.2wt.%Ni and 0.6wt.%Fe in the Al-11Si aluminum alloy formed a Chinese character-shaped Fe-rich enhanced phase.When the Ni content was further increased to 1.6wt.%and the Fe content was increased to 0.8 wt.%,the Fe-rich phase changed to long needle-like structure,leading to severe cracking in the Al matrix and a decrease in the mechanical properties of the alloy.Since the Al-11Si aluminum alloy with 1.2wt.%Ni and 0.6wt.%formed a Chinese character-shaped Fe-rich enhanced phase,the high-temperature tensile property of the alloy was significantly improved.The ultimate tensile strength(UTS)of the Al-11 Si aluminum alloy reached 139 MPa at the test temperature of 350℃.