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 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.

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.

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

Fracture Mechanisms of Bulk Amorphous Metal under Impact Loading

2000 ◽  
Vol 644 ◽  
Author(s):  
Takao Kobayashi ◽  
Donald A. Shockey
Keyword(s):  
Cross Sections ◽  
Metallic Glasses ◽  
Microscopic Analysis ◽  
High Impact ◽  
Fracture Mechanisms ◽  
New Materials ◽  
Deformation And Failure ◽  
Failure Resistance ◽  
Diagnostic Instruments ◽  
Insight Into

AbstractAdvanced diagnostic instruments and analyses applied to failure surfaces and cross sections of bulk metallic glasses (BMGs) can provide insight into the deformation and failure of these materials and assist in prototyping new materials with improved failure resistance. Confocal- optics scanning laser microscopic analysis of conjugate fracture surface topographs suggests that the formation and stretching of ligaments are likely keys to the high impact toughness of Vitreloy.

Effects of Applied Electric Fields on Interface Dynamics and Microstructure Formation During Directional Solidification of BiMn/Bi Eutectic

2000 ◽  
Author(s):  
L. L. Zheng
Keyword(s):  
Electric Field ◽  
Directional Solidification ◽  
Electric Fields ◽  
Microscopic Analysis ◽  
Eutectic Growth ◽  
Macroscopic Model ◽  
Microstructure Formation ◽  
Applied Current ◽  
Thermoelectric Effects ◽  
Interface Dynamics

Abstract This paper is to demonstrate that the presence of an electric field can be used to control materials microstructure formation. Special efforts have been made to identify the foremost process control parameters that affect the interface dynamics, and thermoelectric effects on materials microstructure formation during directional solidification. A computational model that integrates microscopic analysis to macroscopic model has been developed and applied to directional solidification of BiMn/Bi eutectic in the presence of electric fields. Numerical results demonstrated that in addition to process parameters, microstructure formation strongly depends on intensity, polarity and duration of applied current, and it changes spontaneously as an electric field is applied. Predicted patterns of microstructures have qualitatively agreed with the experiments. The results indicate the feasibility of utilizing electric fields to control microstructure formation during eutectic growth.

scholarly journals Finding the weakest link: mechanical sensitivity in a fish cranial linkage system

2018 ◽  
Vol 5 (10) ◽  
pp. 181003 ◽  
Author(s):  
A. Baumgart ◽  
P. Anderson
Keyword(s):  
Morphological Evolution ◽  
Structural Features ◽  
Mechanical Sensitivity ◽  
Weakest Link ◽  
Lower Jaw ◽  
Single Link ◽  
Evolutionary Level ◽  
Variable Influence ◽  
Physical Mechanics ◽  
Insight Into

Understanding the physical mechanics behind morphological systems can offer insights into their evolution. Recent work on linkage systems in fish and crustaceans has suggested that the evolution of such systems may depend on mechanical sensitivity, where geometrical changes to different parts of a biomechanical system have variable influence on mechanical outputs. While examined at the evolutionary level, no study has directly explored this idea at the level of the mechanism. We analyse the mechanical sensitivity of a fish cranial linkage to identify the influence of linkage geometry on the kinematic transmission (KT) of the suspensorium, hyoid and lower jaw. Specifically, we answer two questions about the sensitivity of this linkage system: (i) What changes in linkage geometry affect one KT while keeping the other KTs constant? (ii) Which geometry changes result in the largest and smallest changes to KT? Our results show that there are ways to alter the morphology that change each KT individually, and that there are multiple ways to alter a single link that have variable influence on KT. These results provide insight into the morphological evolution of the fish skull and highlight which structural features in the system may have more freedom to evolve than others.

Influence of thermal stabilization on the solute concentration of the melt in directional solidification

2010 ◽  
Vol 312 (24) ◽  
pp. 3658-3664 ◽  
Author(s):  
Dongmei Liu ◽  
Yanqing Su ◽  
Xinzhong Li ◽  
Liangshu Luo ◽  
Jingjie Guo ◽  
...  
Keyword(s):  
Directional Solidification ◽  
Thermal Stabilization ◽  
Solute Concentration

scholarly journals Concentration-discharge relationships vary among hydrological events, reflecting differences in event characteristics

2020 ◽  
Author(s):  
Julia L. A. Knapp ◽  
Jana von Freyberg ◽  
Bjørn Studer ◽  
Leonie Kiewiet ◽  
James W. Kirchner
Keyword(s):  
Trace Metals ◽  
Major Ions ◽  
Low Frequency ◽  
Solute Concentration ◽  
Biologically Active ◽  
Concentration Data ◽  
Event Scale ◽  
Wide Range ◽  
Insight Into

Abstract. Studying the response of streamwater chemistry to changes in discharge can provide valuable insights into how catchments store and release water and solutes. Previous studies have determined concentration-discharge (cQ) relationships from long-term, low-frequency data of a wide range of solutes. These analyses, however, provide little insight into the coupling of solute concentrations and flow during individual hydrologic events. Event-scale cQ relationships have rarely been investigated across a wide range of solutes and over extended periods of time, and thus little is known about differences and similarities between event-scale and long-term cQ relationships. Differences between event-scale and long-term cQ behavior may provide useful information about the processes regulating their transport through the landscape. Here we analyze cQ relationships of 14 different solutes, ranging from major ions to trace metals, as well as electrical conductivity, in the Swiss Erlenbach catchment. From a 2-year time series of sub-hourly solute concentration data we determined long-term cQ relationships for each solute and compared them to cQ relationships of 30 individual events. The long-term cQ behavior of groundwater-sourced solutes was representative of their cQ behavior during hydrologic events. Other solutes, however, exhibited very different cQ patterns at the event and long-term scale. This was particularly true for trace metals as well as atmospheric and/or biologically active solutes, many of which exhibited highly variable cQ behavior from one event to the next. Most of this inter-event variability in cQ behavior can be explained by factors such as catchment wetness, season, event size, input concentrations, and event-water contributions. We present an overview of the processes regulating different groups of solutes, depending on their origin in and pathways through the catchment. Our analysis thus provides insight into controls on solute variations at the hydrologic event scale.

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