Due to excellent casting performance, low density, and good mechanical propertiesNeng et al., hypoeutectic Al Si alloys are widely used in aerospace and automotive applicationsIn the field of vehicle manufacturing, such as missile mounts, diesel engine bodies, cylinder heads, etc.Modified eutectic Si is a commonly used method to improve the mechanical properties of Al Si alloys. Antimony (Sb) is an effective modifier, sand casting and scholarsWe are committed to studying the metamorphic mechanism of Sb. studyResearch has shown that Sb can promote the nucleation of eutectic Si. Research onIt indicates that after adding Sb, the original nucleation core AlP of eutectic Si disappears, and AlSb becomes the new nucleation core. studyResearch has shown that the appearance of AlSb is a result of Sb’s over modification of eutectic Si.Research shows that Mg3Sb2 can form eutectic SiCore. Research TableThe mechanism of Sb modification in eutectic Si is that Sb adsorbs on the surface of eutectic SiHinder its growth. In short,sand casting although many scholars have studied Sb metamorphismThe mechanism of eutectic Si varies, but opinions vary. The modification of eutectic Si by SbFurther research is needed on the mechanism.
Due to low cost, simple process, and short cycle, gravity sand castingIt is essential in the foundry industry. Composition of Hypoeutectic Al-7Si AlloyWeaving includes nascent α－ Al grains, eutectic Si, nano precipitates and impuritiesXiang.sand casting However, under the conditions of gravity sand casting, there is little research on the effect of Sb onPrimary growth of hypoeutectic Al-7Si alloy α－ The influence of Al grains and eutectic SiResearch has been conducted in this article, with the hope of providing insights into Sb’s application in AsiaIndustrial applications in eutectic Al-Si alloys and the properties of Al-7Si alloysModification and upgrading provide some reference.
Melt the refined aluminum, Al-12Si, and Al-4Sb in the furnace and stir evenly,When controlling the temperature to 710-720 ℃,sand casting add Mg and stir for 3-5 minutesPour the sample after refining. Using direct reading spectroscopy to determine the actual composition of alloysThe results are shown in the table. Using FLUKE2638A data acquisitionThe temperature time curve of solidification is collected by the collector and K-type thermocouple everyCollect three curves. Positive in 1% fluoroboric acid at 25V voltagePreparation of samples with extreme film covering for 5.5 minutes, using BX53MRF-S-type biasObservation of newborn under a light microscope α－ Al grains. Using the standard metallographic sample preparation method to polish the sample, sand casting in order to observe eutectic Si more clearly, the sample is placedSoak in 20% NaOH solution for 5 minutes to remove the surrounding eutectic SiAfter using the Al matrix, TESCANMIRALMS scanning electron microscopyObservation of eutectic Si under a sub microscope; sand casting Observing the common structure through electron backscatter diffractionThe nucleation core of crystalline Si is thinned by ion milling on its sample. adoptRandom wire cutting method for calculating grain size using Image ProPlusThe software has calculated the length and width of eutectic Si,sand casting and has counted over 40Grains and 120 eutectic Si. Utilizing FEITecnaiF20 transparencyObservation of twinning in eutectic Si using a transmission electron microscope, and the sample was also analyzed using ionizationSub milling thinning; sand casting Using the built-in energy spectrometer of this electron microscope to analyze eutectic SiThe chemical composition of.
Temperature time curve of alloy solidification, TAlNIt’s a newborn α－ Nucleation temperature of Al grains, TSiN is the beginning of eutectic reactionTemperature, i.e. the nucleation temperature of eutectic Si. As shown in Figure 1 (a), sand casting Sb has not been addedTAl of Al-7Si alloyN is 619.5 ℃, TSiN is 578.1 ℃.As shown in Figure 1 (b), after adding 0.09% Sb, the performance of Al-7Si alloyTAlN decreases to 611.8 ℃, TSiN decreased to 572.6 ℃.
Conclusion
1) Initial Study on Gravity Sand Casting of Al-7Si Alloy with the Addition of Sbliving α－ The nucleation temperature of Al grains and eutectic Si has decreased; firstliving α－ Al grain nucleation is more difficult, with an average particle size of 319 μ M increasesTo 353 μ M.2) Sb modified eutectic in gravity sand casting Al-7Si alloyThe mechanism of Si is to induce nascent growth α－ The nucleation temperature of Al grains decreases, while Siα－ The solid solubility in Al decreases, sand casting the chemical potential increases, and Si atoms shift from α－ AlThe rate of discharge increases, and the growth rate of eutectic Si accelerates,sand casting ultimately resulting in eutecticCrystal Si becomes shorter and narrower. Sb does not nucleate through its action on eutectic SiThe core and twin exhibit metamorphism.