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高密度脉冲电流对A356铝合金凝固组织的影响 总被引:22,自引:0,他引:22
研究了高密度脉冲电流对A356铝合金凝固组织的影响,实验中对液相线以下溶体的凝固过程在不同阶段进行电脉冲处理。对比实验结果表明:经过电脉冲处理后,A356的合金凝固组织得到明显细化;在同样的电脉冲条件下,凝固组织细化效果与电脉冲放电开始时间有关,凝固过程中放电开始时间越早,凝固组织细化效果越明显;反之,凝固组织细化效果较差;同时,脉冲充电电压越高,凝固组织细化程度越大。定量计算了脉冲电流产生的电磁力并分析了脉冲电流影响凝固组织的作用机制。 相似文献
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高密度脉冲电流作用下LY12铝合金的凝固组织 总被引:22,自引:6,他引:22
研究了高密度脉冲电流作用下LY12铝合金的凝固组织,试验结果表明嵩密度的脉冲电流可明显地改善该合金凝固组织。和未经电流处理的样品相比,其组织明显细化和等轴化,且脉冲电流愈强,且脉冲电流愈强,这种效果愈显著。 相似文献
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Effects of the melt pulse electric current and thermal treatment on solidification structures of A356 alloy were investigated.In the experiments.the low temperature melt(953K and 903K)treated by pulse electric current was mixed with high temperature metl(1223K).By the control experiments,the results show that the solidification structure of A356 alloy is refined apparently by the pulse electric current together with melt thermal treatment process,and the mechanical properties.especially the elongation ratio of the specimen treated is improved greatly.The structure change of the melt by pulse electric current and melt thermal treatment is the main reason for the refinement of the solidification structure of A356 alloy. 相似文献
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建立凝固过程的数学模型来揭示自由晶核的迁移行为。模拟结果表明:在脉冲电流作用下,大多数形成于熔体上表面的晶核将往下迁移并随机分布于Al熔体内部,提供更多的形核质点,进而细化凝固组织晶粒。同时,研究在施加脉冲电流(ECP)时晶核尺寸对晶核分布和细化的影响。小尺寸的晶核同周围熔体一同运动,迁移距离较短;而大尺寸的晶核在脉冲电流作用下以较快的速度相对于周围熔体运动,有利于熔体内部晶粒的细化。该研究有利于加深对脉冲电流细化凝固组织机理的认识。 相似文献
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Pulse magneto-oscillation (PMO) was developed as a novel technique to refine the solidification structure of pure aluminium.Its grain refining mechanism was proposed.The PMO refinement mechanism is that the nucleus falls off from the mould wall and drifts into the melt under the action of PMO.The solidification structure of Al melt depends on the linear electric current density,and also the discharge and oscillation frequencies.The radial pressure of PMO sound wave is the major factor that contributes to the migration of nucleus into the melt. 相似文献
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Ding Hongsheng Zhang Yong Jiang Sanyong Chen Ruirun Zhao Zhilong Guo Jingjie Xu Daming Fu Hengzhi 《中国铸造》2009,6(1)
Three kinds of Al-Si piston alloys were prepared and subjected to pulse electric current treatment (PECT) at different pouring temperatures. Some aspects of the solidification microstructures were examined including the morphology and the distribution of the matrix and the secondary phases by using of optical microscopy (OM), SEM and EDS methods. Results indicate that PECT can refine the grains of α-Al in the alloys as effectively as chemical modification by sodium salt. The processing parameters of PECT on the multi-component Al-Si alloys were then optimized through the testing of tensile strength, elongation and microhardness of the prepared alloys. A new theory was put forward to explain the mechanism of PECT. 相似文献
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The effect of high density pulse electric current(HDPEC)on the solidification structure of the low temperature melt(LTM)of commercial A356 alloy was investigated.In th experiments.the HDPEC was discharged in the LTM(953K,903K and 873K),By the control experiments,the results showed that the solidification structure of the LTM of A356 alloy is refined apparently when the HDPEC is discharged in low temperature melt.However,the holding time of melt treated has an adverse effect on the soliification structure.The longer the holding time of the melt treated with HDPEC,the coarser the microstructure.With the same discharge voltage.the lower the temperature of LTM,the more obscure the refinement of solidification structure.Finally,the mechanism of microstructure refining by HDPEC was analyzed. 相似文献
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1 INTRODUCTIONThecharacteristicthatelectriccurrentpulsepro motesatomdiffusionanddislocationmotionwasgrad uallyrecognizedfromthefailureanalysisonintegrat edcircuitin 1970s[110 ] .Theelectriccurrentpulsewasusedtoincrease plastic property ,improvetheformabilityofless deformablemetals[11,12 ] ,andstudytheeffectsofcurrentpulseonrecrystallization[1318]respectivelyin 1980s .Inthisrespect ,ConradandLaihavedonealotofwork ,inwhichCu ,AlandTiweremainexperimentalmaterialsfordeformationemployedwitha… 相似文献
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电脉冲对金属铝箔的作用 总被引:2,自引:0,他引:2
通过对金属铝箔施加高密度脉冲电流的方法 ,从实验和理论上研究了电脉冲对金属铝箔的作用机制。实验结果表明 ,电脉冲对铝箔能够产生收缩作用 ,铝箔的收缩率与电脉冲充电电压和充电电容以及放电次数有关 ,充电电压越高 ,充电电容越高 ,放电次数越多 ,铝箔的收缩率就越大。分析认为 ,脉冲电流在铝箔中产生的电磁力是导致铝箔收缩的主要原因 ,而脉冲电流产生的焦耳热则不会导致铝箔熔化收缩。 相似文献
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The combined effects of direct current pulsed magnetic field (DC-PMF) and inoculation on pure aluminum were investigated, the grain refinement behavior of DC-PMF and inoculation was discussed. The experimental results indicate that the solidification micro structure of pure aluminum can be greatly refined under DC-PMF. Refinement of pure aluminum is attributed to electromagnetic undercooling and forced convection caused by DC-PMF. With single DC-PMF, the grain size in the equiaxed zone is uneven. However, under DC-PMF, by adding 0.05% (mass fraction) Al–5Ti–B, the grain size of the sample is smaller, and the size distribution is more uniform than that of single DC-PMF. Furthermore, under the combination of DC-PMF and inoculation, with the increase of output current, the grain size is further reduced. When the output current increases to 100 A, the average grain size can decrease to 113 μm. 相似文献
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Li Bo Yin Zhenxing Gong Yongyong Li Kefeng Zheng Hongxing LI Renxing Zhai Qijie 《中国铸造》2011,8(2):172-176
This article discusses the effect of temperature field on the Pulse Magneto-Oscillation (PMO) induced solidification refinement of pure aluminiurn to provide more information for the industrial application of the PMO solidification technology. The temperature field is altered mainly by applied variable cooling conditions and pulse parameters. Experimental results show that the refinement effect in the case of full sand mould applied is weakened with the decreasing of cooling rate, however, in the alternative case, the sand mould whose sand bottom was replaced by a graphite block is favorable to the survival of equiaxed nucleus. The refinement mechanism is discussed in terms of the relationship between temperature field and the formation process of solidified structure.The formation or survival of nucleus depends on both temperature field and Joule heat produced by PMO, both low pulse frequency and high pulse current were experimentally confirmed to be effective; and PMO was demonstrated high potential in industrial application. 相似文献