Distribution Behavior of B and P during Al-Si Melt Directional Solidification with Open-Ended Crucible

2018 ◽  
Vol 37 (3) ◽  
pp. 201-208 ◽  
Author(s):  
Xiaolong Bai ◽  
Boyuan Ban ◽  
Jingwei Li ◽  
Zhijian Peng ◽  
Jian Chen
Keyword(s):  
Directional Solidification ◽  
Concentration Profile ◽  
Segregation Coefficient ◽  
Solidification Temperature ◽  
Segregation Behavior ◽  
Primary Si ◽  
Distribution Behavior

AbstractDistribution behavior of B and P during directional solidification of Al-20Si, Al-30Si and Al-40Si alloys has been investigated. Macrostructure of the Al-Si alloy ingots and concentration profile of elements B and P reveal that the elements segregate to eutectic Al-Si melt during growth of primary Si flakes, and P gradually segregates to the top of the ingots during directional solidification. An apparent segregation coefficient, ka, is introduced to describe the segregation behavior of B and P between the primary Si and the Al-Si melt and compared with thermodynamic theoretical equilibrium coefficients. The apparent segregation coefficients of B and P decrease with increase of solidification temperature.

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.

Segregation Behavior of Metal Impurities During Al-Si Melt Directional Solidification with an Open Ended Crucible

Silicon ◽  
2017 ◽  
Vol 10 (4) ◽  
pp. 1283-1290 ◽  
Author(s):  
Xiaolong Bai ◽  
Boyuan Ban ◽  
Jingwei Li ◽  
Zhiqiang Fu ◽  
Zhijian Peng ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Segregation Behavior ◽  
Metal Impurities

Effect of a transverse magnetic field on primary-Si distribution during directional solidification in hypereutectic Al-Si alloy

2017 ◽  
Vol 118 (5) ◽  
pp. 59001 ◽  
Author(s):  
Shaodong Hu ◽  
Yanchao Dai ◽  
Annie Gagnoud ◽  
Yves Fautrelle ◽  
Rene Moreau ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Directional Solidification ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Primary Si

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.

Velocity and Orientation Dependence of Solute Trapping

1985 ◽  
Vol 57 ◽  
Author(s):  
M. J. Aziz ◽  
J. Y. Tsao ◽  
M. O. Thompson ◽  
P. S. Peercy ◽  
C. W. White
Keyword(s):  
Pulsed Laser ◽  
Orientation Dependence ◽  
Sufficient Accuracy ◽  
Segregation Coefficient ◽  
Solute Trapping ◽  
Impurity Atoms ◽  
Segregation Behavior ◽  
Functional Forms ◽  
Solid Liquid Interface ◽  
Solid Liquid

AbstractThe fraction of impurity atoms in the liquid at the solid-liquid interface that join the crystal, known as the segregation coefficient k, during rapid crystal growth is known to deviate away from the equilibrium value towards unity as the interface speed v increases. Several plausible models have been proposed that account qualitatively for this behavior with different functional forms of k(v). We report measurements of the segregation behavior during rapid solidification following pulsed laser melting of Bi-implanted Si. The velocity dependence and the orientation dependence of the segregation coefficient of Bi in Si has been determined to sufficient accuracy to allow us to distinguish between models. Implications for the mechanism of solute trapping are discussed.

AXIAL SEGREGATION IN UNSTEADY DIFFUSION-DOMINATED SOLIDIFICATION IN A FINITE AMPOULE

2006 ◽  
Vol 20 (18) ◽  
pp. 2551-2560
Author(s):  
ADRIAN NECULAE ◽  
AGNETA M. BALINT
Keyword(s):  
Numerical Simulations ◽  
Directional Solidification ◽  
Binary Alloy ◽  
Finite Length ◽  
Concentration Profile ◽  
Composition Profile ◽  
Microgravity Environment ◽  
Initial Transient ◽  
Axial Segregation ◽  
Infinite Crystal

The paper deals with axial segregation in unsteady diffusion dominated directional solidification from melt of a binary alloy in a finite cylindrical ampoule. The study focuses on the influence of the finite length of the ampoule on the concentration profile in a crystal obtained in a microgravity environment. The results are compared to those reported by Kim et al. [J. Crystal Growth183, 490 (1998)] for an infinite crystal. Numerical simulations are performed for two different situations: the initial transient solidification when the melt is uniform in composition, and the multipass solidification when the crystal is grown from the melt, formed by re-melting a crystal with an initial axial composition profile.

Investigation on the Primary Si Phase Solidification and the Properties of SiCw/Al-18Si Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1275-1278
Author(s):  
Lin Geng ◽  
Hong Mei Wei ◽  
Xue Xi Zhang
Keyword(s):  
Squeeze Casting ◽  
Volume Fraction ◽  
Primary Silicon ◽  
Solidification Behavior ◽  
Scanning Calorimetry ◽  
Solidification Temperature ◽  
Casting Technique ◽  
Microstructure Observation ◽  
Primary Si ◽  
Average Size

SiCw/Al-18Si composites were prepared by squeeze casting technique. SiCw/Al-18Si composites were remelted before solidification. The effects of volume fraction of SiC whisker on solidification behavior of SiCw/Al-18Si composites were investigated by means of differential scanning calorimetry (DSC) technique and microstructure observation. DSC results indicated that the start solidification temperature and primary silicon peak temperature decreased gradually and the degree of supercooling increased with the increasing of SiC whisker content. SiC whisker and Sr decreased the average size of Si phases and improved the mechanical properties of the composites.

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