Numerical Study of the Influence of Diffusion-Governed Growth Kinetics of Ternary Alloy on Macrosegregation

This article is to assess the modeling treatment of the growth kinetics (finite or infinite diffusion in liquid and solid phases) during solidification and its influence on the calculation of macrosegregation. A model of diffusion-governed growth kinetic for ternary alloy is developed and used for this assessment. Solidification of a 2D casting (50 x 50 mm2) of a ternary alloy (Fe-0.45 wt.% C-1.06 wt.%Mn) is considered. The result shows that finite diffusion in liquid, important for the initial stage of solidification, plays very important role in the formation of macrosegregation. Moreover, the role of the finite diffusion kinetics in the formation of macrosegregation shows differently in the two extreme cases of solidification structures (columnar or equiaxed).

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Formation of Interfacial Reaction Layers in Al2O3/SS 430 Brazed Joints Using Cu-7Al-3.5Zr Alloys

Metals ◽

10.3390/met8120990 ◽

2018 ◽

Vol 8 (12) ◽

pp. 990 ◽

Cited By ~ 1

Author(s):

Hoejun Heo ◽

Hyeonim Joung ◽

Keeyoung Jung ◽

Chung-Yun Kang

Keyword(s):

Liquid Phase ◽

Interfacial Reaction ◽

Eutectic Temperature ◽

Liquid Phases ◽

430 Stainless Steel ◽

Brazed Joints ◽

Solid Phases ◽

Α Al2o3 ◽

Kinetics Of ◽

Liquid And Solid Phases

The formation of interfacial reaction layers was investigated in an α-Al2O3/430 stainless steel (SS430) joint brazed using a Cu-7Al-3.5Zr active brazing alloy. Brazing was conducted at above its eutectic temperature of 945 °C and below liquidus 1045 °C, where liquid and solid phases of the brazing alloys coexists. At 1000 °C, the liquid phase of the brazing alloy was wet onto the α-Al2O3 surface. Zr in the liquid phase reduced α-Al2O3 to form a continuous ZrO2 layer. As the dwell time increased, Zr in the liquid phases near α-Al2O3 interface was used up to thicken the reaction layers. The growth kinetics of the layer obeys the parabolic rate law with a rate constant of 9.25 × 10−6 cm·s−1/2. It was observed that a number of low yield strength Cu-rich particles were dispersed over the reaction layer, which can release the residual stress of the joint resulting in reduction of crack occurrence.

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Densification Behavior and Microstructural Development of Nano-Agglomerate Powder during Sintering

Materials Science Forum ◽

10.4028/www.scientific.net/msf.534-536.505 ◽

2007 ◽

Vol 534-536 ◽

pp. 505-508 ◽

Cited By ~ 7

Author(s):

Yun Sung Kang ◽

B.H. Cha ◽

H.G. Kang ◽

Jai Sung Lee

Keyword(s):

Volume Fraction ◽

Diffusion Path ◽

Microstructural Development ◽

Densification Behavior ◽

Diffusion Kinetics ◽

Sintering Process ◽

Enhanced Diffusion ◽

Agglomerate Powder ◽

Kinetics Of

Densification behavior of nano-agglomerate powder during pressureless sintering of Fe-Ni nanopowder was investigated in terms of diffusion kinetics and microstructural development. To understand the role of agglomerate boundary for sintering process, densification kinetics of Fe-Ni nano-agglomerate powder with different agglomerate size was investigated. It was found that activation energy for densification process was lower in the small-sized agglomerate powder. The increase in the volume fraction of inter-agglomerate boundary acting as high diffusion path might be responsible for the enhanced diffusion process.

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Calculation of Gallium-Arsenic-Metal Phase Diagrams

MRS Proceedings ◽

10.1557/proc-204-225 ◽

1990 ◽

Vol 204 ◽

Author(s):

James D. Scofield ◽

J. E. Davison ◽

S. R. Smith

Keyword(s):

Free Energy ◽

Phase Diagrams ◽

Ternary Alloy ◽

Regular Solution ◽

Alloy System ◽

Energy Functions ◽

Solid Phases ◽

Solution Parameters ◽

Liquid And Solid Phases ◽

Alloy Systems

ABSTRACTContact metallizations for space-based GaAs solar cells must survive at high temperatures for several minutes. Which metallizations will survive can be predicted by properly calculated phase diagrams instead of performing hundreds of reactions. A method for calculating the ternary temperature constitution phase diagrams Is briefly explained and the phase diagrams are calculated for two Ga-As-X alloy systems. The free energy functions of the liquid and solid phases are approximated by the regular solution theory. The phase diagrams of the three binary alloy systems which form the boundaries of the ternary alloy system are utilized to calculate the binary regular solution parameters. The free energy functions for the ternary liquid and solid phases are expressed In terms of the binary regular solution parameters. The temperature and composition of the liquidus and solidus boundaries for the ternary alloy systems are calculated from these free energy functions. Calculated results are presented for the Ga-As-Ag and the Ga-As-Ge systems.

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Effect of bismuth on the growth kinetics of intermetallic compounds in Sn-3.5Ag solder joints: A growth kinetic model

Metals and Materials International ◽

10.1007/bf03027315 ◽

2004 ◽

Vol 10 (2) ◽

pp. 123-131 ◽

Cited By ~ 8

Author(s):

Joo-Youl Huh ◽

Sang-Uk Han ◽

Chang-Yong Park

Keyword(s):

Kinetic Model ◽

Intermetallic Compounds ◽

Growth Kinetics ◽

Growth Kinetic ◽

Solder Joints ◽

Kinetics Of

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Growth kinetics of primary and secondary solid phases in Sr(NO3)–H2O peritectic system

Journal of Crystal Growth ◽

10.1016/s0022-0248(03)01307-1 ◽

2003 ◽

Vol 255 (3-4) ◽

pp. 386-391 ◽

Cited By ~ 2

Author(s):

Koji Maiwa ◽

Hiroaki Nakamura ◽

Hideo Kimura ◽

Akimitsu Miyazaki

Keyword(s):

Growth Kinetics ◽

Solid Phases ◽

Kinetics Of

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Growth Kinetic Limitations During Rapid Solidification

MRS Proceedings ◽

10.1557/proc-8-15 ◽

1981 ◽

Vol 8 ◽

Cited By ~ 2

Author(s):

William J. Boettinger

Keyword(s):

Growth Rate ◽

Metallic Glass ◽

Growth Kinetics ◽

Slow Rate ◽

Growth Kinetic ◽

Eutectic Growth ◽

Diffusion Kinetics ◽

Velocity Dependence ◽

Microstructural Effects ◽

Rapidly Solidified

ABSTRACTThe importance of growth kinetics in the development of the microstructure of rapidly solidified alloys is described. Growth kinetics are conveniently divided into diffusion kinetics and interface attachment kinetics. The former, which are used extensively for the analysis of slow rate solidification, can be extended to high solidification rates to predict some microstructural features; e.g., the limitations on eutectic growth rate which can promote the formation of metallic glass, and the reduction of microsegregation. At the highest rates interface attachment kinetics must be included. Some microstructural effects of the velocity dependence of the partition coefficient will be described.

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