The Influence Of Alloying Element On 306 Al Alloy Under The Condition Of Vacuum And Melt Overheating Treatment

The 306 alloy are one kind of aluminium - silicon - nickel alloy, this alloy has low absorption cross section of thermal neutron, high anti-high lukewarm water corrosion property, high tensile strength in both room-temperature and high temperature environment, good press-working characteristics and so on. It is a proper jacketing material for tube and plate element in the water-cooled reactor.The first step of this experiment is carrying on melt overheated processing of Al-11Si-1.1Ni-1.5Fe alloy, taking the tensile strength and the elongation ratio under heat treatment condition as the standard, selecting the superheating temperature that can obtain outstanding combination performance, thus determine the melt overheated smelting craft of this alloy. During the experiment, through changing the contents of Ni, Fe and the LPC misch metal element, study the changing elements content how to influence 306 alloy characteristics. Finally, through adding different trace elements (Mg, Ti, Zr, RE) in the Al-11Si-1.1Ni-0.2Fe alloy, observe the trace element how to influence the 306 alloy mechanical properties and Microstructure.The author adopt the methods such as melt overheated processing,flash set, facilities such as optics metallographic microscope and scanning electron microscope, analysis methods such as energy spectrum analysis and fracture analysis, to system research the influences that different element and different ingredient content impose on 306 alloy. The influence factors include melt structure, processing temperature of melt, Ni, Fe and trace element. The author closely studiesthe influences to 306A1 alloy coagulation organization and mechanical properties.On the bases of experiment and theoretical analysis, the author achieved thefollowing conclusions:(1) Carrying on melt overheated processing to the alloy under 1050℃, the Al-11Si-l.lNi-1.5Fe alloy will obtain the best combination performance, phase Si becomes spheroidization, phase Fe becomes remarkable refinement. The fracture section of tensile specimen is typically brittle failure appearance. (2)By changing the Ni content of the alloy, the author discovered that with Ni content's increasing, the alloy room-temperature tensile strength increases, the elongation ratio reduces.(3) By changing the Fe content of the alloy, the author discovered that with Fecontent's increasing, both the alloy-room temperature tensile strength and the elongation ratio also reduces.(4) Adding grains refining elements such as Ti, Zr, Mg, RE to the alloy separatelyor together, the achieved mechanical properties and the metallographic analysis showed that except the Mg element, other elements had little influence on the alloy. This is because formation Mg₂Si disperse distribution under the heat treated condition, thus enhances the alloy mechanical properties remarkably.(5) Adding the LPC misch metal to the Al-11Si-1.1Ni-1.5Fe alloy, the authordiscovered when the RE content is 0.43%, the alloy mechanical properties are high, and the Microstructure is fine.