Effect of Fe Contents on Microstructure,Thermal Conductivity and Mechanical Properties of Hypoeutectic Al-Ni Alloy
Al-Ni alloy is a widely used high-pressure die-cast aluminum alloy system for high thermal conductivity applications,and the influence of Fe content on the thermal conductivity of Al-Ni alloy is very important.In this paper,the effect of different Fe contents on microstructure,thermal conductivity and mechanical properties of hypoeutectic Al-4Ni alloys were studied.The results showed that the microstructure inAl-4Ni alloy was primary α-Al and(α-Al+Al3Ni)eutectic.As the Fe content increased to 0.5％,the eutectic microstructure became(α-Al+Al3Ni)binary eutectic and(α-Al+Al3Ni+Al9NiFe)ternary eutectic.When the Fe content exceeded 0.75％,the primary Al9NiFe phase and halo aluminum dendrite were formed,and the eutectic microstructure became(α-Al+Al9NiFe)binary eutectic and(α-Al+Al3Ni+Al9NiFe)ternary eutectic.With the addition of Fe,thermal conductivity of Al-4Ni-xFe alloy declined,which was mainly related to the solubility of iron in the α-Al matrix of the alloy and the content and morphology of the A19NiFephase.In terms of mechanical properties,with the increase of Fe,yield strength of Al-4Ni-xFe increased,and the elongation slowly decreased first and then dropped sharply.This was mainly due to the formation of A19NiFe primary phase in the alloy,which accelerated the crack propagation.Above all,Al-4Ni-0.5Fe alloy with a good trade-off on thermal conductivity and mechanical properties had the best comprehensive property.
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