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

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.

Experiment Research on Removing Metal Impurities of the Pot Material in Vacuum Directional Solidification

2011 ◽  
Vol 675-677 ◽  
pp. 89-92
Author(s):  
Wen Hui Ma ◽  
Xiang Yang Mei ◽  
Kui Xian Wei ◽  
Shao Yu Tang
Keyword(s):  
Directional Solidification ◽  
Theoretical Distribution ◽  
Experimental Results ◽  
Experiment Research ◽  
Crystal Silicon ◽  
Experimental Distribution ◽  
Silicon Ingot ◽  
Metal Impurities ◽  
Complex Utilization ◽  
Solidification Furnace

The pot material of Sb-doped n-type mono-crystal silicon was purified by our selfassembled vacuum directional solidification furnace. In the experimental, the pulling rate was 7μm/s, 10μm/s, 20μm/s, 30μm/s and 40μm/s, respectively. The experimental concentration of Sb, Al and Fe at 0.3 proportion of silicon ingot bottom to the top is detected and the theoretical concentration is calculated. The experimental results show that the pulling rate causes a great effect to concentration of Sb and a small effect to concentration of Fe. At the same time, the theoretical distribution concentration and experimental distribution concentration were compared. The experimental route provided a promising idea for complex utilization of the pot material.

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.

The Influence of Cooling Water Flow to Purify the Metallurgical Grade Silicon by Directional Solidification

2013 ◽  
Vol 712-715 ◽  
pp. 784-787
Author(s):  
Tao Lin ◽  
Da Jun Zhang ◽  
Chun Yan Duan ◽  
Dong Liang Lu
Keyword(s):  
Directional Solidification ◽  
Water Flow ◽  
Removal Efficiency ◽  
Cooling Water ◽  
Experimental Results ◽  
Metallurgical Grade Silicon ◽  
Density Of Dislocations ◽  
Silicon Ingot ◽  
Metal Impurities ◽  
Grade Silicon

Directional solidification is one of the most important processes to purify the impurities in the metallurgical grade silicon. A lot of factors could influence the result of directional solidification. In this paper, we researched cooling water flow which could influence the result of directional solidification. We have studied three data of cooling water flow which influenced the results of the removal efficiency of the impurities. Experimental results showed that cooling water flow can influence the density of dislocations and twins in the ingot. The metal impurities of Al, Fe and Ca were concentrated in the middle of the silicon ingot mostly. It was inferred that the bigger cooling water flow was better to the efficiency of the purification in the experiment.

Improving the Purity of Multicrystalline Silicon by Using Directional Solidification Method

2018 ◽  
Vol 911 ◽  
pp. 51-55
Author(s):  
Peng Ting Li ◽  
Shi Qiang Ren ◽  
Zi Long Wang ◽  
Yi Tan
Keyword(s):  
Crystal Growth ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Removal Rate ◽  
Large Temperature ◽  
Metal Impurity ◽  
Silicon Ingot ◽  
Fast Speed ◽  
Metal Impurities ◽  
Large Temperature Gradient

Large temperature gradient was introduced to improve the removal rate of metal impurity in silicon ingot during direction solidification. The concentration of metal impurities in the silicon ingot with a large temperature gradient is 0.96 ppmw. The solidification time is reduced by 20% due to the fast speed of crystal growth improved; meanwhile the purity is increased by 64%.

Experiment Research on Purifying Metallurgical Grade Silicon and Crystal Growth in Directional Solidification

2009 ◽  
Vol 79-82 ◽  
pp. 1213-1216 ◽  
Author(s):  
Xiang Yang Mei ◽  
Wen Hui Ma ◽  
Kui Xian Wei ◽  
Yong Nian Dai
Keyword(s):  
Crystal Growth ◽  
Directional Solidification ◽  
Crystalline Silicon ◽  
Acid Leaching ◽  
Raw Material ◽  
Metallurgical Grade Silicon ◽  
Silicon Ingot ◽  
Metal Impurities ◽  
Segregation Effect ◽  
Grade Silicon

The main raw material of solar energy is multi-crystalline silicon. Directional solidification technique is one important technological process of metallurgy purification technology for multi-crystalline silicon. It can purify metallurgical grade silicon by removing metal impurities and control crystal growth at the same time. In experiment, metallurgical grade silicon by acid leaching pre-treatment, was purified by our self-assembled directional solidification furnace. The sample was analyzed by electron-prode micro analysis (EPMA). According to the results, the removal efficiency of Fe and Al is 96.3% and 96.7%, respectively. The removing mechanism of metal impurities and the difference between theory value and experiment value were also discussed. The segregation effect in directional solidification is the reason of removing Fe, but analgesic effects of the segregation effect combined with vacuum volatilization are that of removing Al. When the silicon ingot was cooled down, lengthways section of silicon ingot was cut and etched, crystal growth was studied. The results indicate that columnar crystal growth shows diverging tendency from the bottom to the top of silicon ingots, and solidification interface shape is convex. The reasons may be the nucleation of new crystals on crucible sidewall is very serious and the pulling rate is too high.

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