Study of Heterogeneous Nucleation of α-Al on Grain Refiner Particles during Rapid Solidification

2006 ◽  
pp. 251-256
Author(s):  
P. Cizek ◽  
B.J. McKay ◽  
P. Schumacher
Keyword(s):  
Rapid Solidification ◽  
Heterogeneous Nucleation ◽  
Grain Refiner

scholarly journals Nucleation Behavior of a Single Al-20Si Particle Rapidly Solidified in a Fast Scanning Calorimeter

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2920
Author(s):  
Qin Peng ◽  
Bin Yang ◽  
Benjamin Milkereit ◽  
Dongmei Liu ◽  
Armin Springer ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Heterogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Solidification Behavior ◽  
Nucleation Kinetics ◽  
Nucleation Behavior ◽  
Nucleation Undercooling ◽  
Primary Si

Understanding the rapid solidification behavior characteristics, nucleation undercooling, and nucleation mechanism is important for modifying the microstructures and properties of metal alloys. In order to investigate the rapid solidification behavior in-situ, accurate measurements of nucleation undercooling and cooling rate are required in most rapid solidification processes, e.g., in additive manufacturing (AM). In this study, differential fast scanning calorimetry (DFSC) was applied to investigate the nucleation kinetics in a single micro-sized Al-20Si (mass%) particle under a controlled cooling rate of 5000 K/s. The nucleation rates of primary Si and secondary α-Al phases were calculated by a statistical analysis of 300 identical melting/solidification experiments. Applying a model based on the classical nucleation theory (CNT) together with available thermodynamic data, two different heterogeneous nucleation mechanisms of primary Si and secondary α-Al were proposed, i.e., surface heterogeneous nucleation for primary Si and interface heterogenous nucleation for secondary α-Al. The present study introduces a practical method for a detailed investigation of rapid solidification behavior of metal particles to distinguish surface and interface nucleation.

Refinement Effect and Mechanism of AZ31 Magnesium Alloy by Electromagnetic Stirring under the Effect of Grain-Refiner

2013 ◽  
Vol 631-632 ◽  
pp. 556-561 ◽  
Author(s):  
Sheng Yuan Gao ◽  
Shi Lian Qu ◽  
Yue Yuan ◽  
Bao Qin Fu
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Heterogeneous Nucleation ◽  
Holding Time ◽  
Electromagnetic Stirring ◽  
Az31 Magnesium Alloy ◽  
Grain Refiner ◽  
Nucleation Sites ◽  
Continuously Cast ◽  
Refinement Effect

The effects of electromagnetic stirring and Al4C3grain refiner on the grain refinement of semi-continuously cast AZ31 magnesium alloy were discussed in this investigation. The results indicate that electromagnetic stirring has effective refining effect on the grain size of AZ31 magnesium alloy under the effect of Al4C3grain refiner. Electromagnetic stirring can “activate” the Al4C3particles, resulting in more heterogeneous nucleation sites for the primary α-Mg grains. But, longer holding time can “inactivate” the Al4C3particles, and the optimal experimental holding time is 60 min in the present investigation. The activated rate of the electromagnetic under the experimental condition ρ2=1.65%.

Effect of Al-5Ti-1B Grain Refiner Addition on the Formation of Intermetallic Compounds in Al-Mg-Si-Mn-Fe Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 53-57 ◽  
Author(s):  
Zhong Ping Que ◽  
Yun Wang ◽  
Y.P. Zhou ◽  
L. Liu ◽  
Z. Fan
Keyword(s):  
Intermetallic Compounds ◽  
Heterogeneous Nucleation ◽  
Ternary Eutectic ◽  
Experimental Results ◽  
Solidification Microstructure ◽  
Chinese Script ◽  
Secondary Branch ◽  
Grain Refiner ◽  
Binary Eutectic ◽  
Fe Alloys

The effect of Al-5Ti-1B grain refiner addition on solidification microstructure, especially the formation of the binary eutectic (Al)+Al15(Fe,Mn)3Si2was investigated in Al-5Mg-2Si-0.7Mn-1.1Fe (wt.%) alloy. The experimental results showed that the solidification microstructure were consisted of primary α-Al phase, inter dendritic binary eutectic (Al)+Al15(Fe,Mn)3Si2, and ternary eutectic (Al+Mg2Si+Al15(Fe,Mn)3Si2). The heterogeneous nucleation of the primary (Al) phase in the alloys was greatly enhanced by the Al-5Ti-1B grain refiner, refining the (Al) grains significantly. The subsequent binary eutectic was nucleated on these refined (Al) phase. Consequently, the size of Al15(Fe,Mn)3Si2phase with a Chinese script morphology in the binary eutectic was greatly refined, without much change in the secondary branch spacing.

Eco-Friendly Grain Refinement for A3003 Alloy

2009 ◽  
Vol 620-622 ◽  
pp. 89-92
Author(s):  
Hoon Cho ◽  
Jae Hong Ha ◽  
Byoung Soo Lee ◽  
Sung Ho Chang ◽  
Je Sik Shin
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Grain Growth ◽  
Heterogeneous Nucleation ◽  
Aluminum Matrix ◽  
Graphite Crucible ◽  
Holding Time ◽  
Ti Alloy ◽  
Grain Refiner ◽  
Prolonged Holding

Eco-friendly grain refinement of A3003 alloy was studied by addition of non-toxic Al-Ti alloy because of toxic-fluorine in Al-Ti-B alloys which used as a representative grain refiner for aluminum and its alloys. TiAl3 phase in Al-Ti alloy bring to decrease grain size of A3003 alloy. But, grain growth occurred with prolonged holding time due to the solution of Ti into aluminum matrix. In contrast, lasting grain refinement of A3003 alloy was occurred in graphite crucible. It can be mentioned that carbon comes from graphite crucible was combined with Ti solute in aluminum melt and then TiC acts as a heterogeneous nucleation for A3003 alloy.

scholarly journals Grain refinement of commercially pure aluminum with addition of Ti and Zr elements based on crystallography orientation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhongwei Chen ◽  
Kang Yan
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Pure Aluminum ◽  
Al Alloys ◽  
Orientation Relationships ◽  
Grain Refiner ◽  
Heterogeneous Nucleation Site ◽  
Edge Matching ◽  
Commercially Pure ◽  
Al Matrix

Abstract The edge-to-edge matching (E2EM) model and electron back-scatter diffraction (EBSD) technique are used to explore the grain refinement mechanism of commercially pure Al through the addition of Ti and Zr elements. EBSD results show that there are favorable crystallography orientation relationships (ORs) between both Al3Ti and Al3Zr particles with α-Al matrix. Due to these ORs Al3Ti and Al3Zr particles act as the heterogeneous nucleation site during solidification nucleation of Al–Ti and Al–Zr alloys, respectively. Furthermore, both Al3Ti and Al3Zr particles have small values of interplanar spacing mismatch and interatomic spacing misfit with respect to α-Al matrix by using E2EM. It shows that micro-addition of Ti and Zr element is efficient heterogeneous nucleation refiner in commercial purity Al or Al alloys. Besides, there may be some other mechanisms in grain refinement of Al alloys with addition of Ti grain refiner.

scholarly journals Nucleation behaviour and microstructure of single Al-Si12 powder particles rapidly solidified in a fast scanning calorimeter

2021 ◽  
Author(s):  
Bin Yang ◽  
Qin Peng ◽  
Benjamin Milkereit ◽  
Armin Springer ◽  
Dongmei Liu ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Heterogeneous Nucleation ◽  
Cooling Rates ◽  
Solidification Behaviour ◽  
Nucleation Undercooling ◽  
In Situ Investigation ◽  
Solidification Processes ◽  
Powder Particles ◽  
Rapidly Solidified

AbstractThe understanding of rapid solidification behaviour, e.g. the undercooling versus growth velocity relationship, is crucial for tailoring microstructures and properties in metal alloys. In most rapid solidification processes, such as additive manufacturing (AM), in situ investigation of rapid solidification behaviour is missing because of the lack of accurate measurement of the cooling rate and nucleation undercooling. In the present study, rapid solidification of single micro-sized Al-Si12 (mass%) particles of various diameters has been investigated via differential fast scanning calorimetry employing controllable cooling rates from 100 to 90,000 K s−1 relevant for AM. Based on nucleation undercooling and on microstructure analysis of rapidly solidified single powder particles under controlled cooling rates, two different heterogeneous nucleation mechanisms of the primary α-Al phase are proposed. Surface heterogeneous nucleation dominates for particles with diameter smaller than 23 μm. For particles with diameter larger than 23 μm, the nucleation of the primary α-Al phase changes from surface to bulk heterogeneous nucleation with increasing cooling rate. The results indicate that at large undercoolings (> 95 K) and high cooling rates (> 10,000 K s−1), rapid solidification of single particle can yield a microstructure similar to that formed in AM. The present work not only proposes new insight into rapid solidification processes, but also provides a theoretical foundation for further understanding of microstructures and properties in additively manufactured materials.

Development of Grain Refinement in Aluminium Field

2012 ◽  
Vol 706-709 ◽  
pp. 402-407
Author(s):  
Bao De Sun ◽  
Yan Feng Han ◽  
Jun Wang
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
First Principles ◽  
Preparation Method ◽  
First Principles Calculations ◽  
Commercial Purity ◽  
Grain Refiner ◽  
The Poor ◽  
Purity Aluminium ◽  
Commercial Purity Aluminium

Some progresses of grain refinement in aluminium field in our group are involved in this paper. We invented a new preparation method of Al-Ti-B grain refiner with the application of high-intensity ultrasound in the preparation reaction. Owing to the optimization of TiB2 particles morphology in the prepared grain refiner, the commercial purity aluminium grains can be refined as small as 45μm, which is superior to the limiting level of the present commercial grain refiner, 120μm. First-principles calculations on the Al/TiB2 interface prove that the larger Al/TiB2 interfacial energy than that between α-Al and aluminium melt is responsible for the poor heterogeneous nucleation of α-Al on TiB2 particles with only TiB2 particles in melt. When there is redundant solute Ti in the melt, it is theoretically revealed that the spontaneous segregation of solute Ti on TiB2 particles plays an important role in the heterogeneous nucleation.

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