Research Of Heat Treatment Strengthening Mechanism Of Semi-solid Hypereutectic Al-Fe Alloy

Al-Fe alloy has a broad application prospects, because of light weight, heat-resistant,wear-resistant. When produced by ordinary casting methods, the mechanical properties ofthe alloy is too low, especially ductility due to the formation of coarse flakiness Al3Fe. Soit cannot meet the actual project needs. This paper studies the impact of forming processand heat treatment on the mechanical properties and wear resistance of Al-5.5Fe-2.5Cu andAl-5.5Fe-4Cu alloy, and Optical Microscope, SEM and TEM have been used to analyzemicrostructures. Research on this subject has important practical significance and a certaintheoretical value of application of Al-Fe alloy.The results indicate that the content of Cu element has a certain impact on alloysmicrostructure and properties. The properties of Al-5.5Fe-4Cu alloys by three differentforming methods are significantly better than corresponding Al-5.5Fe-2.5Cu alloys. Itshows that appropriate increase content of Cu within a certain range improvedmicrostructure and properties of alloys. Al-5.5Fe based alloy by semi-solid formingproperties better than as-cast, hot extruded forming, and the grain size is smaller, shape andsize of Al3Fe phase have improved significantly. Properties of semi-solid Al-5.5Fe basedalloys after T6heat treatment decreases significantly. Through EDX spectrum analysis wefound that a lot of Cu element has gathered around Al3Fe phase. Needle-like thick Al3Fephase blocks movement of dislocation, so a large number of dislocations accumulatearound Al3Fe phase, and the high temperature of solution heat treatment increase diffusioncoefficient of Cu element, then it gathers around Al3Fe phase by dislocations. The growthup of rich-Cu is the main reason for the decline of mechanical properties of alloys. Tensilestrength of semi-solid Al-5.5Fe base alloy is significantly improved after T1heat treatment,and grain becomes smaller and uniform. Cu element is not gathered around Al3Fe phaseafter low temperature aging treatment, but precipitation as strengthening phase Al2Cuformation. So it improves the mechanical properties of alloys. Analysis on wear resistance of semi-solid Al-5.5Fe base alloys shows that after T1heat treatment the alloy’s wear weights and fluctuation of friction factor are very small,and the furrow of surface is shallow. The wear performance is significantly better than thatof no heat treatment and T6heat treatment alloys. This shows that T1heat treatment canimprove wear resistance of Al-5.5Fe base alloy.