An investigation for structure transformation in electric pulse modified liquid aluminum

Qi, Jingang; Wang, Jianzhong; He, Lingfeng; Zhao, Zuofu; Du, Huiling

doi:10.1016/j.physb.2010.12.010

Cited by 16 publications

(4 citation statements)

References 5 publications

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“…The first theory focuses on the application of ECP to the solidification interval, and it mainly involves crystallization rain theory and dendrite breaking theory [22,23,27]. The second type focuses on the application of ECP to the melt interval and is based on the inoculation theory proposed by Wang et al [28,29,30]. They have pointed out that ECP can distort the external electron layer of the crystal embryo (cluster) in pure metal melts, and that this distortion facilitates the refinement of grains [30].…”

Section: Introductionmentioning

confidence: 99%

Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt

Geng

Zhou

et al. 2018

Materials

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In this work, an electric current pulse (ECP) of 500A was applied on a hypereutectic high chromium cast iron (HHCCI) melt before it began to solidify, and the effect of ECP on primary carbides was investigated. The characteristics of the primary carbides were analyzed by X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), transmission electron microscopy (TEM), micro hardness tester, and other techniques. The results showed that ECP not only refined the primary (Cr, Fe)7C3 carbides, but also decreased the average content of Cr in the primary carbides. At the same time, the average value of micro hardness of the primary carbides increased by about 84 Kgf/mm2, which contradicts existing knowledge that hardness increases with an increase in Cr content. XRD analysis showed that the crystal structure of the primary carbides did not change. The results of EPMA indicated that the Cr/Fe ratio gradually decreased from the center to the edges of the carbide particles. Further investigation revealed that the uneven distribution of elements caused by ECP led to an increase in defects (including twins, antiphase boundaries, and dislocations). This increase in defect density is the main reason for the increase in micro hardness instead of the expected decrease. The mechanism of the change in primary carbides was analyzed in detail in this paper, which has provided a new method for the refinement of primary carbides and for improving the properties of primary carbides.

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Section: Introductionmentioning

confidence: 99%

Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt

Geng

Zhou

et al. 2018

Materials

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“…The effect of AECP treatment with respect to the different solidification stages should be considered in detail. During the liquid phase stage above the liquidus temperature, there may be an inoculation effect which can improve the nucleation rate and refine the solidification structure [28]. However, the inoculation effect had not been observed when an AECP with 2070 A was applied to the solidification of Al-7Si alloy [24].…”

Section: Resultsmentioning

confidence: 99%

Research on Grain Refinement in Hypoeutectic Al-Si Alloy during Solidification under an Alternating Electric Current Pulse

Zhang

et al. 2019

Metals

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Experiments on transient directional solidification were carried out to study the columnar to equiaxed transition (CET) in Al-7Si alloy without and with an alternating electric current pulse (AECP). Without AECP, the macrostructure consists of typical columnar and equiaxed zones, separated by a near horizontal plane. As the AECP is applied during solidification, an additional fine equiaxed zone (FEZ) occurs in the as-cast macrostructure. From measured temperature profiles, cooling rate and temperature gradient are determined. It is found that CET occurs for a critical value of the cooling rate, which is observed to be about 0.14 K·s−1 in the present investigation. Furthermore, the macrostructural observation with mold for embedding the mesh plate demonstrates that the major factor responsible for the formation of fine equiaxed grains is the detachment of crystal nuclei from the upper contact surface and the lateral wall. The detachment is in turn ascribed to electric current-associated free energy change (ΔGe)-induced the driving force F.

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“…Simultaneously, many researchers have investigated the solidification microstructure refinement through ECP, but few reports exist on the effect of ECP treatment on the solid solubility of alloys. It is generally considered that the liquid structure transition plays an important role to the alloy ingot grain refinement, and many experiments have indicated that the metal casting structure is most closely related to its liquid matrix [13].…”

Section: Introduction mentioning

confidence: 99%

Effect of High Density Electric Current Pulse on Solidification of Cu-37.4 wt.%Pb Monotectic Alloy Melt

Geng

Sun

et al. 2019

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The effect of high-density electric current pulse (ECP) on the solidification of Cu-37.4 wt.%Pb monotectic alloy melt was investigated. The microstructure formation mechanisms of ECP were clarified according to liquid metal cluster theory. The results demonstrated that with ECP treatment, the microstructure of Cu-Pb monotectic alloy became finer, the distribution of Pb phase in the matrix was more even and the solute trapping was significantly apparent. Based on the metal liquid cluster theory under ECP, the solid solubility increase result might be due to the salvation clusters increase under the action of pulse current, leading to the binding force increase among solute atoms and solvent atoms. Simultaneously, the aforementioned results were verified through the Differential Scanning Calorimetry (DSC) curve analysis. The results of hardness test, anti-friction test and wear- resistance test show that the ECP can enhance the hardness, improve the properties of anti-friction and wear-resistance of the alloy.

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An investigation for structure transformation in electric pulse modified liquid aluminum

Cited by 16 publications

References 5 publications

Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt

Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt

Research on Grain Refinement in Hypoeutectic Al-Si Alloy during Solidification under an Alternating Electric Current Pulse

Effect of High Density Electric Current Pulse on Solidification of Cu-37.4 wt.%Pb Monotectic Alloy Melt

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