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Article
Publication date: 12 February 2018

Sijo M.T., Jayadevan K.R. and Sheeja Janardhanan

Stir casting is a promising technique used for the manufacture of Al-SiC metal matrix composites. The clustering of reinforcement particles is a serious concern in this…

Abstract

Purpose

Stir casting is a promising technique used for the manufacture of Al-SiC metal matrix composites. The clustering of reinforcement particles is a serious concern in this production method. In this work, mushy-state solidification characteristics in stir casting are numerically simulated using computational fluid dynamics techniques to study the clustering of reinforcement particles.

Design/methodology/approach

Effects of process parameters on the distribution of particles are examined by varying stirrer speed, volume fraction of reinforcement, number of blades on stirrer and diameter ratio (ratio of crucible diameter to stirrer diameter). Further, investigation of characteristics of cooling curves during solidification process is carried out. Volume of fluid method in conjunction with a solidification model is used to simulate the multi-phase fluid flow during the mushy-state solidification. Solidification patterns thus obtained clearly indicate a strong influence of process parameters on the distribution of reinforcement particles and solidification time.

Findings

From the simulation study, it is observed that increase in stirrer speed from 50 to 150 rad/s promotes faster solidification rate. But, beyond 100 rad/s, stirrer speed limit, clustering of reinforcement particles is observed. The clustering of reinforcement particles is seen when volume fraction of reinforcement is increased beyond 10 per cent. When number of blades on stirrer are increased from three to five, an increase in solidification rate is observed, and an uneven distribution of reinforcement particles are observed for five-blade geometry. It is also seen from the simulation study that a four-blade stirrer gives a better distribution of reinforcement in the molten metal. Decrease in diameter ratio from 2.5 to 1.5 promotes faster solidification rate.

Originality/value

There is 90 per cent closeness in results for simulation study and the published experimental results.

Details

World Journal of Engineering, vol. 15 no. 1
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 1 February 2013

Hao Yu and Dongkai Shangguan

As a literature review article, the purpose of this paper is to highlight the intricate interaction and correlation between the interconnection microstructure and the…

Abstract

Purpose

As a literature review article, the purpose of this paper is to highlight the intricate interaction and correlation between the interconnection microstructure and the failure mechanism. It is therefore critical to summarize all the challenges in understanding solder solidification of interconnections.

Design/methodology/approach

Literature review.

Findings

Solidification of solder interconnections is therefore critical because it is the process during which the solder interconnection is formed. The as‐solidified microstructure serves as the starting point for all failure modes. Because of the miniaturization of electronics, the interconnection size decreases continuously, already to such a range that solder solidification takes place remarkably differently from the bulk ingot, on which solidification studies have been focused for decades. There are many challenges in understanding the solidification of tiny solder interconnections, including the complex metallurgical system, dynamic solder composition, supercooling and actual solidification temperature, localized temperature field, diverse interfacial IMC formation, and so on, warranting further research investment on solder solidification.

Originality/value

This paper provides a critical overview of the concerns in solidification study for lead‐free solder interconnection. It is probably an article initiating more attention towards solidification topics.

Details

Soldering & Surface Mount Technology, vol. 25 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 17 October 2018

Mohammad M. Hosseini and Asghar B. Rahimi

Reducing discrepancy between energy demand and supply has been a controversial issue among researchers. Thermal energy storage is a technique to decrease this difference…

Abstract

Purpose

Reducing discrepancy between energy demand and supply has been a controversial issue among researchers. Thermal energy storage is a technique to decrease this difference to increase the thermal efficiency of systems. Latent heat thermal energy storage has interested many researchers over the past few decades because of its high thermal energy density and constant operating temperature. The purpose of this paper is to provide a numerical study of the solidification process in a triplex tube heat exchanger containing phase change material (PCM) RT82.

Design/methodology/approach

A two-dimensional transient model was generated using finite volume method and regarding enthalpy-porosity technique. After that, a detailed and systematic approach has been presented to modify longitudinal fins’ configuration to enhance heat transfer rate in PCMs and reducing solidification time. The numerical results of this study have been validated by reference experimental results.

Findings

The ultimate model reduced solidification time up to 21.1 per cent of the Reference model which is a substantial improvement. Moreover, after testing different arrangements of rectangular fins and studying the flow pattern of liquid PCM during solidification, two general criteria was introduced so that engineers can reach the highest rate of heat transfer for a specified value of total surface area of fins. Finally, the effect of considering natural convection during solidification was studied, and the results showed that disregarding natural convection slows down the solidification process remarkably in comparison with experimental results and in fact, this assumption generates non-real estimation of solidification process.

Originality/value

The arrangement of the fins to have the best possible solidification time is the novelty in this paper.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 February 1999

Xiaoli Zhang and T. Hung Nguyen

The solidification of a superheated fluid‐porous medium contained in a rectangular cavity is studied numerically. The bottom and side walls of the cavity are insulated…

Abstract

The solidification of a superheated fluid‐porous medium contained in a rectangular cavity is studied numerically. The bottom and side walls of the cavity are insulated while the top wall is maintained at a constant temperature below the freezing point of the saturating fluid. The study is focused on the effects of superheat on the development of natural convection and heat transfer during the solidification process. For a fluid initially at a temperature above the freezing point, the results obtained by neglecting convection overpredicts the solidification time by about 12 percent for a Rayleigh number of 800. When convection is taken into account, it is found that the solidification process consists of three distinct regimes: the conduction regime, convection regime and the solidification of the remaining fluid that can be described by the Neumann solution for the solidification of a fluid at its freezing point. The numerical simulations are based on the Darcy‐Boussinesq equations, using the front tracking method in a transformed coordinate system. The entire solidification process is described in terms of the evolutions of the streamlines and isotherm patterns, the maximum and average temperatures of the fluid, the interface position, and the heat transfer rate. The parametric domain covered by these simulations is 0 ≤ Ra ≤ 800, 0 ≤ Stl ≤ 0.67, Sts = 0.3 and XL = 1 where Ra is the Rayleigh number, Stl the liquid Stefan number, Sts the solid Stefan number, and XL the aspect ratio of the cavity.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 9 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 6 January 2012

Piyasak Damronglerd, Yuwen Zhang and Mo Yang

The purpose of this paper is to solve solidification of liquid copper saturated in porous structure fabricated by sintered steel particles using a temperature‐transforming…

Abstract

Purpose

The purpose of this paper is to solve solidification of liquid copper saturated in porous structure fabricated by sintered steel particles using a temperature‐transforming model (TTM).

Design/methodology/approach

The convection in the liquid region is modeled using Navier‐Stokes equation with Darcy's term and Forchheimer's extension. The effect of natural convection is considered using the Boussinesq approximation. For the solid region, the velocity is set to zero by the Ramped Switch‐Off Method (RSOM). The model was validated by comparing the results with existing experimental and numerical results with gallium as phase change material and packed glass beads as porous structure. Solidification of liquid copper saturated in sintered copper particles is then simulated and the effects of various parameters on solidification process were studied.

Findings

The results indicate that the stronger convection effects are shown for the cases with high Raleigh number or high Darcy's number. However, when either Raleigh number or Darcy's number is reduced to below a certain order of magnitude, the solidification becomes conduction‐controlled.

Originality/value

This work is the first application of the TTM to solve solidification in porous media, which can find its application in post‐processing of laser sintered parts.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 22 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 14 June 2021

Jeffrey B. Allen

In this work, with a goal to ultimately forward the advancement of additive manufacturing research, the author applies the Wheeler-Boettinger-McFadden model through a…

Abstract

Purpose

In this work, with a goal to ultimately forward the advancement of additive manufacturing research, the author applies the Wheeler-Boettinger-McFadden model through a progressive series of increasingly complex solidification problems illustrating the evolution of both dendritic as well as columnar growth morphologies. For purposes of convenience, the author assumes idyllic solutions (i.e. the excess energies associated with mixing solid and liquid phases can be neglected).

Design/methodology/approach

In this work, the author applied the phase-field model through a progressive series of increasingly complex solidification problems, illustrating the evolution of both dendritic as well as columnar growth morphologies. Beginning with a non-isothermal treatment of pure Ni, the author further examined the isothermal and directional solidification of Cu–Ni binary alloys.

Findings

(1) Consistent with previous simulation results, solidification simulations from each of the three cases revealed the presence of parabolic, dendrite tips evolving along directions of maximum interface energy. (2) For pure Ni simulations, changes in the anisotropy and noise magnitudes resulted in an increase of secondary dendritic branches and changes in the direction of propagation. The overall shape of the primary structure tended also to elongate with increased anisotropy. (3) For simulations of isothermal solidification of Ni–Cu binary alloys, the development of primary and secondary dendrite arm formation followed similar patterns associated with a pure substance. Calculations of dendrite tip velocity tended to increase monotonically with increasing anisotropy in accordance with previous research. (4) Simulations of directional solidification of Ni–Cu binary alloys with a linear temperature profile demonstrated the presence of cellular dendrites with relatively weak side-branching. The occurrence of solute trapping was also apparent between the primary dendrite columns. Dendrite tip velocities increased with increasing cooling rate.

Originality/value

This research, particularly the section devoted to directional solidification of binary alloys, describes a novel numerical framework and platform for the parametric analysis of various microstructural related quantities, including the effects due to changes in temperature gradient and cooling rate. Both the evolution of the phase and concentration are resolved.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 5
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 1 May 1999

M. M’Hamdi, H. Combeau and G. Lesoult

The general aim of this work is to calculate the extent of the equiaxed zone in continuously cast steel products. Free equiaxed grains can grow only in undercooled liquid…

Abstract

The general aim of this work is to calculate the extent of the equiaxed zone in continuously cast steel products. Free equiaxed grains can grow only in undercooled liquid regions. Undercooling of the bulk liquid occurs because the columnar dendrite tips growing from the mould reject solutes in the liquid. The specific aim of this contribution is to calculate the thermal and physical state of continuously cast steel long products assuming a columnar solidification mode, taking into account the tip undercooling at the solidification front. A 2‐D heat transfer model has been developed where the columnar solidification mode is assumed. The calculation of the undercooling at the advancing solidification front is coupled with the heat transfer equation. The comparison between the results of the present model and the classical heat transfer model indicates the importance of modelling the undercooling phenomenon. The influence of the secondary cooling has also been studied.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 9 no. 3
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 18 November 2013

Shu Li and Ping Wu

The aim of the present work is to study the effect of processing conditions on solidification path and resultant microstructure and further predict the solidification

Abstract

Purpose

The aim of the present work is to study the effect of processing conditions on solidification path and resultant microstructure and further predict the solidification behavior of gas-atomized Sn-5mass%Pb droplets.

Design/methodology/approach

Combined with previous models for in-flight droplet nucleation and non-equilibrium solidification, a simulation method is applied to four typical containerless solidification conditions with helium, nitrogen or argon gas at two different gas jet velocities, in the presence of 10 or 500 ppm oxygen. The simulation outputs distribution of primary dendrite composition, tip velocity and tip radius with radial distance from the nucleation point, and the fraction solid at the end of recalescence and the post-recalescence duration. Both surface and internal nucleation are considered. The possible dendritic fragmentation in the post-recalescence stage is also discussed.

Findings

Result indicates that dendritic fragmentation is not likely to occur in droplets solidifying along the paths considered in the simulation.

Originality/value

The simulation method applies to any droplet-based solidification process for which droplet cooling schedule is known and thus provides a scientific basis for powder quality assurance.

Details

Multidiscipline Modeling in Materials and Structures, vol. 9 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 24 June 2021

Rafael Kakitani, Cassio Augusto Pinto da Silva, Bismarck Silva, Amauri Garcia, Noé Cheung and José Eduardo Spinelli

Overall, selection maps about the extent of the eutectic growth projects the solidification velocities leading to given microstructures. This is because of limitations of…

Abstract

Purpose

Overall, selection maps about the extent of the eutectic growth projects the solidification velocities leading to given microstructures. This is because of limitations of most of the set of results when obtained for single thermal gradients within the experimental spectrum. In these cases, associations only with the solidification velocity could give the false impression that reaching a given velocity would be enough to reproduce a result. However, that velocity must necessarily be accompanied by a specific thermal gradient during transient solidification. Therefore, the purpose of this paper is to not only project velocity but also include the gradients acting for each velocity.

Design/methodology/approach

Compilation of solidification velocity, v, thermal gradient, G, and cooling rate, Ṫ, data for Sn-Cu and Sn-Bi solder alloys of interest is presented. These data are placed in the form of coupled growth zones according to the correlated microstructures in the literature. In addition, results generated in this work for Sn-(0.5, 0.7, 2.0, 2.8)% Cu and Sn-(34, 52, 58)% Bi alloys solidified under non-stationary conditions are added.

Findings

When analyzing the cooling rate (Ṫ = G.v) and velocity separately, in or around the eutectic composition, a consensus cannot be reached on the resulting microstructure. The (v vs. G) + cooling rate diagrams allow comprehensive analyzes of the combined v and G effects on the subsequent microstructure of the Sn-Cu and Sn-Bi alloys.

Originality/value

The present paper is devoted to the establishment of (v vs. G) + cooling rate diagrams. These plots may allow comprehensive analyses of the combined v and G effects on the subsequent microstructure of the Sn-Cu and Sn-Bi alloys. This microstructure-processing mapping approach is promising to predict phase competition and resulting microstructures in soldering of Sn-Cu and Sn-Bi alloys. These two classes of alloys are of interest to the soldering industry, whereas manipulation of their microstructures is considered of utmost importance for the metallurgical quality of the product.

Details

Soldering & Surface Mount Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 February 1996

Tianhong Ouyang and Kumar K. Tamma

Thermal solidification processes are an important concern in today’smanufacturing technology. Because of the complex geometric nature ofreal‐world problems, analytical…

Abstract

Thermal solidification processes are an important concern in today’s manufacturing technology. Because of the complex geometric nature of real‐world problems, analytical techniques with closed‐form solutions are scarce and/or not feasible. As a consequence, various numerical techniques have been employed for the numerical simulations. Of interest in the present paper are thermal solidification problems involving single or multiple arbitary phases. In order to effectively handle such problems, the finite element method is employed in conjunction with adaptive time stepping approaches to accurately and effectively track the various phase fronts and describe the physics of phase front interactions and thermal behaviour. In conjunction with the enthalpy method which is employed to handle the latent heat release, a fixed‐grid finite element technique and an automatic time stepping approach which uses the norm of the temperature distribution differences between adjacent time step levels to control the error are employed with the scale of the norm being automatically selected. Several numerical examples, including single and multiple phase change problems, are described.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 6 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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