Process Optimization And Performance Of A356 Alloy By Enhancing And Compounding Treatments

Aluminum alloy is the commonly material used in automotive wheel,in this paper,microstructure and its influence law was investigated by used A356 as matrix via micro-alloying and compound modification and refinement,then direct quenching after casting and artificial aging,to achieve the purpose of weight reduction and energy saving,which with excellent mechanical properties.The aluminum matrix composites are investigated from Al-K₂ZrF₆-KBF₄ and Al-K₂ZrF₆-B₂O₃ systems via in-situ reaction under pulsed magnetic field and high-power ultrasonic field.The OEM,SEM,XRD and DSC analyzing technologies are used to determine the solidification structures of the as-prepared composites,the morphologies and distributions of the in situ reinforcement particles in the aluminum matrix.The in situ reaction mechanisms under pulsed magnetic field and high-power ultrasonic field for fabricating particle reinforcement aluminum matrix composites are investigated,and the in situ dynamics mechanisms are established.The in situ tension courses of the as-prepared composites are carried out and the fracture models of the composites are built.The results indicate that the microstructure was improved by adding Mn,with refined acicularβ-Al₅FeSi to short-bar shapeα-Al(Mn,Fe)Si.A356 alloy was refined and modified by adding 0.2%Al-5Ti-1B,0.2%Al-10Sr and 0.2%Al-10RE.The grains are refined,and the Si phase is grain shape with well dispersed in melt.Tensile strength is higher by nearly 27.1%,which reached to 268.1MPa and elongation is higher by nearly 31.6%,reached to 5.61%by adding 0.2%Al-5Ti-1B,0.2%Al-10Sr and 0.2%Al-10RE. The results of the analysis of the tensile fracture morphology indicate that the tensile fracture form is visible dimple fracture character.The results indicate that the particles synthesized from the A356-K₂ZrF₆-KBF₄ system are ZrB₂ under 850℃,which are hexagonal and uniformly distributed in the matrix,the size is about 1-3μm.The particles synthesized from the A356-K₂ZrF₆-B₂O₃ system are Al₃Zr,Al₂O₃,and ZrB₂ under 900℃.The size of long strip Al₃Zr particles is about 3-5μm,and spherical Al₂O₃ particles are less than 3-5μm.The SEM and XRD of the water-quench samples results indicate that the in-situ melt reaction mechanism for the A356-K₂ZrF₆-KBF₄ system with is reaction-cracking-diffusion.The mechanical properties test results show that the tensile strength and the elongation of the as-prepared composites are obviously increased with the increase of ultrasonic power and the pulsed magnetic field intensity.For the A356-K₂ZrF₆-KBF₄ system,when ultrasonic power is 1.5kW,the tensile intensity of composites is higher by nearly 18.16%than that of without treatment,reached 264.1MPa,and the elongation is higher by nearly 12%,reached 4.71%.For the A356-K₂ZrF₆-KBF₄ system,with the pulsed magnetic field intensity,the tensile intensity of composites is higher by nearly 22.1%than that of without treatment,reached 273.1MPa,and the elongation is slight reduced to 3.96%.The results of the analysis of the tensile fracture morphology indicate that the tensile fracture form with ultrasonic power is fracture character.The tensile fracture form with the pulsed magnetic field intensity is ductile fracture.The strength mechanisms with physical field of the as-prepared aluminum matrix composites are Orowan strength,fine-grained strength,solution strength and dislocation strength.