| Hypoeutectic Al-Si alloy is widely used in high pressure tanks, high-speed pillow beamand other parts because of its lower elastic coefficient, better conductivity and so on. Thisarticle research the effect of different modifier on the microstructure and mechanicalproperties and analyze the modification mechanism of ZL101alloy.The results prove that Sr modification exist severe tendency to hydrogen absorption,and the alloy attain the lowest density after modification treatment90min. The addition ofRE improve the phenomenon of tendency to hydrogen absorption, increase the density ofalloy. Sb+Te modification there is no tendency to hydrogen absorption, Sb+Te+RE ternarycomplex modification increase the density of alloy remarkably.The morphology of eutectic silicon by bulky flake or needle into a tiny short rods orfibrous through Sr modification, and greatly improve the number of eutectic silicon branch.Average length and width of eutectic silicon is about9.0μm and2.0μm after Sr modification.The addition of RE improve the metamorphism effect, further reduce the size of the eutecticsilicon, and promote the eutectic silicon branch. Average length and width of eutectic siliconis about7.0μm and1.7μm after RE modification. Sb+Te modified can change the growthmode of silicon eutectic, average length and width of eutectic silicon is about23.0μm and2.6μm after Sb+Te modification; Average length and width of eutectic silicon is about16.0μm and2.2μm after Sb+Te+Re modification.Sb+Te+RE ternary complex modification increase alloy comprehensive mechanicalproperties remarkably, brinell hardness, tensile strength and elongation of alloy can reach to68.7HB,173.1MPa and4.79%, increased by28.89%,34.81%and94.72%compared withunmodified alloy. Conductivity of Sr+RE complex modification alloy increase to40.80%IACS, increased by19.75%compared with unmodified alloy, and increased by7.65%~13.68%compared with other modification alloy. The incubation period of Srmetamorphic is about30min, and in this period in alloy metamorphism is not completely.Metamorphic recession occur after morphology5h. The addition of RE can eliminate theincubation period, and increase the effective metamorphic time to more than7h.Eutectic silicon fusing and turn into spheroidization or granular and its tip deactivatedafter heat treatment. The size of eutectic silicon decreased after heat treatment. The mechanical properties and electrical conductivity of alloy obviously improve, andSb+Te+RE complex modification with T6heat treatment increase the mechanical propertiesof alloy at most obviously, and Sb+RE complex modification increase the conductivity ofalloy at most obviously. |
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