scholarly journals Enhancing Segregation Behavior of Impurity by Electromagnetic Stirring in the Solidification Process of Al-30Si Alloy

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 155 ◽  
Author(s):  
Qingchuan Zou ◽  
Ning Han ◽  
Zixu Zhang ◽  
Jinchuan Jie ◽  
Fan Xu ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Solidification Process ◽  
Rotating Magnetic Field ◽  
Electromagnetic Stirring ◽  
Growth Interface ◽  
Segregation Behavior ◽  
Metallurgical Silicon ◽  
Primary Si ◽  
Equilibrium Solidification ◽  
Manageable Method

Increasing the removal efficiency of impurities during non-equilibrium solidification of hypereutectic Al-Si alloy remains a great challenge for the upgrading of metallurgical silicon (MG-Si) to solar grade Si (SOG-Si). Hence, a manageable method was provided to enhance the segregation behavior of impurities at the interface front of primary Si/Al-Si melt by introducing a rotating magnetic field (RMF) in the present work. Experimental results showed that electromagnetic stirring can improve the removal efficiency of impurities while achieving the separation of primary Si. The apparent segregation coefficients of the major impurities Fe, Ti, Ca, Cu, B and P were reduced to 7.5 × 10−4, 4.6 × 10−3, 7.9 × 10−3, 3.5 × 10−3, 0.1 and 0.16, respectively, under RMF of 25 mT and cooling rate of 2.5 °C/min. We confirmed that improving the transport driving force of impurities in the growth interface front of primary Si is an effective way to improve the segregation behavior of impurities, which would bring us one step closer to exploiting the economic potential of the Al-Si alloy solidification refining.

scholarly journals Controlling Segregation Behavior of Primary Si in Hypereutectic Al-Si Alloy by Electromagnetic Stirring

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1129 ◽  
Author(s):  
Qingchuan Zou ◽  
Hao Tian ◽  
Zixu Zhang ◽  
Chengzhuo Sun ◽  
Jinchuan Jie ◽  
...  
Keyword(s):  
Temperature Field ◽  
Temperature Gradient ◽  
Coupling Effect ◽  
Raw Materials ◽  
Morphological Evolution ◽  
Electromagnetic Stirring ◽  
Solidification Structure ◽  
Continuous Growth ◽  
Segregation Behavior ◽  
Primary Si

Controlling the segregation behavior of primary Si in the solidification process of hypereutectic Al-Si alloy is crucial for enhancing the design ability of the solidification structure. To explore the separation condition and morphological evolution of primary Si in detail, a series of experiments concerning the coupling effect of a temperature field and electromagnetic stirring on the segregation behavior of primary Si were carried out. Experimental results show that the temperature field and fluid flow in the melt are two key points for controlling the segregation behavior of primary Si. The establishment of a temperature gradient in the Al-Si melt is a precondition for realizing the separation of primary Si. On the basis of the temperature gradient, the electromagnetic stirring can further strengthen the separation effect for primary Si, forming a Si-rich layer with 65~70 wt.% Si content. The formation of the Si-rich layer is a continuous growth process of primary Si by absorbing Si atoms from Al-Si melt with the help of electromagnetic stirring. The separation technology for primary Si is proposed to realize the segregation control of primary Si, which not only broadens the application of Al-Si alloys in the functionally gradient composites but also provides a low-cost supply strategy of Si raw materials for the solar photovoltaic industry.

scholarly journals Liquid Metal Flow Under Traveling Magnetic Field—Solidification Simulation and Pulsating Flow Analysis

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 532
Author(s):  
Evgeniy Shvydkiy ◽  
Egbert Baake ◽  
Diana Köppen
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Neutron Radiography ◽  
Metal Flow ◽  
Flow Analysis ◽  
Solidification Process ◽  
Electromagnetic Stirring ◽  
Pulsation Frequency ◽  
Conductive Liquid ◽  
Traveling Magnetic Field

Non steady applied magnetic field impact on a liquid metal has good prospects for industry. For a better understanding of heat and mass transfer processes under these circumstances, numerical simulations are needed. A combination of finite elements and volumes methods was used to calculate the flow and solidification of liquid metal under electromagnetic influence. Validation of numerical results was carried out by means of measuring with ultrasound Doppler velocimetry technique, as well as with neutron radiography snapshots of the position and shape of the solid/liquid interface. As a result of the first part of the work, a numerical model of electromagnetic stirring and solidification was developed and validated. This model could be an effective tool for analyzing the electromagnetic stirring during the solidification process. In the second part, the dependences of the velocity pulsation amplitude and the melt velocity maximum value on the magnetic field pulsation frequency are obtained. The ability of the pulsating force to develop higher values of the liquid metal velocity at a frequency close to the MHD resonance was found numerically. The obtained characteristics give a more detailed description of the electrically conductive liquid behaviour under action of pulsating traveling magnetic field.

Dendrite Growth Characteristics and Segregation Control of Bearing Steel Billet with Rotational Electromagnetic Stirring

2017 ◽  
Vol 36 (4) ◽  
pp. 339-346 ◽  
Author(s):  
Yu Xu ◽  
Xiu-Jie Xu ◽  
Zhuang Li ◽  
Tao Wang ◽  
An-Yuan Deng ◽  
...  
Keyword(s):  
Continuous Casting ◽  
Solidification Process ◽  
Bearing Steel ◽  
Dendrite Growth ◽  
Growth Characteristics ◽  
Electromagnetic Stirring ◽  
Secondary Dendrite Arm Spacing ◽  
Steel Billet ◽  
Dendrite Fragmentation ◽  
Equiaxed Grain

AbstractThe effects of rotational electromagnetic stirring (R-EMS) on dendrite growth characteristics and segregation control of bearing steel billet were investigated in continuous casting. The results show that applying R-EMS can promote columnar-equiaxed transition, increase the region of the equiaxed grain from 5 % to 45 %, decrease the secondary dendrite arm spacing (SDAS), and reduce the segregation of both carbon and sulfur. Meanwhile, the fragments of dendrite arms induced by R-EMS are observed. The length of the dendrite fragmentation is approximately 1.5 mm, 7–10 times the SDAS. Some fragments can partially remelt to become effective nuclei, and some fragments survive the solidification process.

Flow Control during Solidification of AlSi-Alloys by Means of Tailored AC Magnetic Fields and the Impact on the Mechanical Properties

2014 ◽  
Vol 790-791 ◽  
pp. 384-389
Author(s):  
Dirk Räbiger ◽  
Bernd Willers ◽  
Sven Eckert
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Grain Size ◽  
Magnetic Fields ◽  
Flow Field ◽  
Phase Distribution ◽  
Solidification Process ◽  
Quantitative Information ◽  
Rotating Magnetic Field ◽  
The Impact

This paper presents an experimental study which in a first stage is focused on obtaining quantitative information about the isothermal flow field exposed to various magnetic field configurations. Melt stirring has been realized by utilizing a rotating magnetic field. In a second step directional solidification of AlSi7 alloys from a water-cooled copper chill was carried out to verifythe effect of a certain flow field on the solidification process and on the resulting mechanical properties. The solidified structure was reviewed in comparison to an unaffected solidified ingot. Measurements of the phase distribution, the grain size, the hardness and the tensile strength were realized. Our results demonstrate the potential of magnetic fields to control the grain size, the formation of segregation freckles and the mechanical properties. In particular, time–modulated rotating fields show their capability to homogenize both the grain size distribution and the corresponding mechanical properties.

Effect of Rotating Magnetic Field on Microstructure Evolution of Pb-Bi Alloys

2011 ◽  
Vol 311-313 ◽  
pp. 600-608
Author(s):  
Zhao Chen ◽  
Xiao Li Wen ◽  
Chang Le Chen
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Microstructure Evolution ◽  
Solidification Process ◽  
Nucleation And Growth ◽  
Primary Phase ◽  
Rotating Magnetic Field ◽  
Growth Behaviour ◽  
Solidification Behaviour ◽  
40 Hz

Solidification behaviour of Pb-Bi alloys under rotating magnetic field (RMF) was investigated experimentally to understand the effect of the frequency of RMF on the nucleation and growth behaviour. It was found that, as the increase of the rotating frequency, the grains are fragmented and refined gradually until a transition from columnar to equiaxed microstructures happens at a rotating frequency of 40 Hz. Moreover, the Bi concentration of the primary phase decreases and macrosegregation is eliminated effectively with RMF. These are due to the effect of RMF on the nucleation, growth and fluid flow in the solidification process.

scholarly journals Segregation and Morphological Evolution of Si Phase during Electromagnetic Directional Solidification of Hypereutectic Al-Si Alloys

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 10 ◽  
Author(s):  
Weiyan Jiang ◽  
Wenzhou Yu ◽  
Jie Li ◽  
Zhixiong You ◽  
Chunmei Li ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Morphological Evolution ◽  
Microscopic Analysis ◽  
Solute Concentration ◽  
Constitutional Supercooling ◽  
Metallic Alloys ◽  
Crystal Growth Rate ◽  
Segregation Behavior ◽  
Primary Si ◽  
Insight Into

Understanding the Si segregation behavior in hypereutectic Al-Si alloys is important for controlling the micro- and macrostructures of ingots. The macrosegregation mechanism and morphological evolution of the primary Si phase were investigated during electromagnetic directional solidification (EMDS). Both numerical simulations and experimental results strongly suggested that the severe macrosegregation of the primary Si phase was caused by fluid flow and temperature distribution. Microscopic analysis showed that the morphological evolution of the Si crystal occurred as follows: planar → cellular → columnar → dendritic stages during EMDS. Based on constitutional supercooling theory, a predominance area diagram of Si morphology was established, indicating that the morphology could be precisely controlled by adjusting the values of temperature gradient (G), crystal growth rate (R), and solute concentration (C0). The results provide novel insight into controlling the morphologies of primary Si phases in hypereutectic Al-Si alloys and, simultaneously, strengthen our understanding of the macrosegregation mechanism in metallic alloys.

scholarly journals Fundamental Study on Segregation Behavior in U–Zr–Fe–O System during Solidification Process

2019 ◽  
Vol 18 (3) ◽  
pp. 111-118 ◽  
Author(s):  
Ayako SUDO ◽  
Fumiki MIZUSAKO ◽  
Kuniyoshi HOSHINO ◽  
Takumi SATO ◽  
Yuji NAGAE ◽  
...  
Keyword(s):  
Solidification Process ◽  
Fundamental Study ◽  
Segregation Behavior
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