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Electric Pulse Modification of Al-22Si alloy of recession

, That is standing with the melt time inoculation effect gradually disappeared when the holding time 8Orain, its morphology and the organization without the electric pulse treatment is similar to the average size from 77.35m rose to 143.67 \m. Key words electric pulse modification; primary si phase; clusters; pregnant recession CLC TG111.4; TG146.21 literature flag code A Article ID 1001-2249 (2007) 12 a O912 a high silicon Al-O2 Si alloys have good mechanical properties and thermal expansion coefficient, etc., is an ideal material for production of piston [】 thirty]. In 1998, Wang Jianzhong proposed electric pulse modification (EPM) method, and the development of a clean liquid field of metal processing technology. The team of aluminum, copper, aluminum-copper alloy, high carbon steel, electrical steel were studied _5 name], the organization has been significantly refined. However, the same electric pulse modification melt there decline,[link widoczny dla zalogowanych], thereby affecting and restricting the technology applications in industrial production. the literature of the electric pulse on the ZL108 alloy _l, KS282 ... solidification of alloys, but the effect of electric pulses of high silicon Al-Si alloys recession of the system rarely reported. The topics to A1-22Si alloy studied primary Si phase is investigated after electric pulse of different aging time of the primary Si shape, size and other effects, which initially set the electrical pulse modification A1 -22Si alloy recession characteristics. 1 test methods test for the A1-22Si alloy alloy in 3kw resistance furnace for melting high purity graphite crucible material. heated to 850 ℃ for 10rain, by the C: Cl addition to gas refining. lower melting body temperature to 750 ℃, the pulse generator, electrodes inserted into the melt surface to about 3mm or so (see Figure 1), after standing 0,[link widoczny dla zalogowanych],5,20,40,80 rain were pouring into the metal mold Figure 1 pulsed electric field processing melt diagram 1. molten metal 2. crucible 3. electrode 4. resistance furnace 5. pulse generator 6. temperature controller (the cast iron type, preheating temperature is 250 ℃). metallographic samples taken from the step-shaped sample central erosion metallographic polishing in Axiovert200MAT microscope on, the average size of primary Si measured by image analysis system to complete M1AP3. 2 Results and discussion 2.1 aging time of the AI-22Si Alloy Chart 2 for the electric pulse of different standing time after the A1-22Si Alloy. It can be seen from Figure 2, untreated sample solidification thick lath segregation status of primary Si was distributed in the matrix, after immediately pour the small homogeneous sample, but with the standing time after treatment, the primary Si phase gradually thick. When holding time 80rain, the organization essentially similar with the untreated sample. For the average size of primary Si statistical calculations show that, with the standing time,[link widoczny dla zalogowanych], the average size of primary Si becomes larger, its trends and changes in microstructure of the same tendency (see Table 1). Table 1AI · 22Si alloy average size of primary sj, um2.2 Discussion and Analysis of the results of the low heat melt is composed of different composition and structure of ordered clusters with their dollars between the various groups were randomly distributed with a disorder composed. Singh et al [1 found that Al-Si alloys Si atoms exist in the melt Group, also studies have shown that Si atoms have a relatively stable structure of clusters, namely, the relationship between existing clusters to meet the magic number shell structure [1. According to the views of cast metal genetics, A1-22Si alloy Si clusters in segregation is reflected alloy solid-liquid carrier of the genetic characteristics of a solid, but also the core of the primary sources of Si nucleation. When the A1-22Si alloy melt dispersion in Si clusters smaller size is large,[link widoczny dla zalogowanych], reflects Debu significant surface effect. At this point Si clusters in Al-Si alloy melt equilibrium composition z, when the electric pulse in the melt, the instantaneous electric field in pulse discharge under the influence of large-scale Si Received date :2007 clusters -07-08 Foundation item: National Natural Science Foundation of China (50174028); Liaoning Provincial Natural Science Foundation of China (001080) First Author: Heli Jia, male, born in 1977, Ph.D., Beijing University of Technology of Metallurgical and Ecological Engineering, Address: Liaoning University of Technology of Materials and Chemical Engineering, Liaoning Jinzhou (121001), Tel :0416-4199650, E-mail: [link widoczny dla zalogowanych]

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