Effect of Chemical Composition on Apparent Viscosity of Semi-solid Metals

Hirai, Masazumi; Takebayashi, Katsuhiro; Yoshikawa, Yuji

doi:10.2355/tetsutohagane1955.78.10_1538

Cited by 5 publications

(8 citation statements)

References 8 publications

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“…Constitutional undercooling is responsible for dendritic growth. In other words, by controlling alloy chemical composition, the type and percentage of solute elements, constitutional undercooling and thus the growth rate and morphology of primary phase, dendritic or equiaxed growth, may be controlled [42].…”

Section: Alloy Chemistry and Pouring Temperaturementioning

confidence: 99%

The implication of rheology in semi-solid metal processes: An overview

Lashkari

Ghomashchi

2007

Journal of Materials Processing Technology

113

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Section: Alloy Chemistry and Pouring Temperaturementioning

confidence: 99%

The implication of rheology in semi-solid metal processes: An overview

Lashkari

Ghomashchi

2007

Journal of Materials Processing Technology

113

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“…It is believed [90,99] the higher concentration of solute in the alloy brings more rosette type feature and consequently the volume fraction of liquid trapped between the primary crystals increases. Such phenomenon brings higher viscosity within the slurry.…”

Section: Composition (Co)mentioning

confidence: 99%

“…With the formation of dendrites, as mentioned before, the apparent viscosity of slurry increases and rheocasting in this condition becomes more difficult. In other words, rheocasting of alloys with lower solute concentration would be easier [90].…”

Section: Composition (Co)mentioning

confidence: 99%

“…In other words with controlling alloy chemical composition, i.e. the type and percentage of solute elements, constitutional undercooling and thus the growth rate and morphology of primary phase, dendritic or equiaxed growth, may be controlled [11,90].…”

Section: Chemistry and Pouring Temperaturementioning

confidence: 99%

“…An empirical equation has also been proposed to relate the viscosity and compositional factors [90,99]. Furthermore, alloy composition could affect dendrite coherency point, by postponing it with increasing solute concentration [82].…”

Section: Composition (Co)mentioning

confidence: 99%

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rheological behavior of semi-solid A356 alloy /

Lashkari¹

2006

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The semi-solid-metal, SSM, processing deals with semi solid slurries, in which non dendritic solid particles are dispersed in a liquid matrix with apparent viscosity values near to that of liquid. It is able to flow easily under pressure and fills complicated die cavities to manufacture sound as-cast products with high integrity. The SSM slurry is prepared through different methods. In the current study conventional casting and the SEED process were employed to produce SSM billets with different morphologies of primary a-Al phase in A356 Al-Si alloy. For conventional casting, a range of solid particle morphologies, microstructure, were realized through variation of pouring temperature while for the SEED billets, as a new patent of ALCAN international for semi solid casting, changes in the morphology were achieved by control of process parameters during solidification of the melt.In order to investigate the morphological evolution due to the effect of different process parameters, pouring temperature and swirling intensities, the SSM billets prepared by both methods were studied using quantitative metallography. The microstructure of SSM A356 alloy has also been characterized using an innovative method, parallel plate compression viscometry, where a correlation was made between the morphology and viscosity. The main objective of the current research was the implication of rheological principles to study the deformation behavior of A3 5 6 alloy at different morphologies and fraction of solid, while treating the SSM billets as Newtonian and Non-Newtonian fluids respectively. Furthermore, two empirical relationships were proposed to underline the correlation among the viscosity, and fraction solid and its morphology. In order to further confirm the reliability of the tests results in this research and to highlight that the sample size has no effect on the final deformation and viscosity values, a new series of tests were performed using two sets of specimens with aspect ratio (height/diameter) of 0.4 and 1.8.It was found that conventional billets cast at low pouring temperature of 615°C comprise fine and equiaxed grains while the billets cast at high pouring temperature of 695°C have dendritic structure. For SEED billets, swirling refined the primary a-Al dendrites and promoted the formation of rosette and/or globular a-Al particles with increasing swirling speed. The effectiveness of swirling speed may be due to reduction in segregation of alloying elements at the solidification front and better heat transfer between the mold and bulk of liquid to establish a shallow temperature gradient resulting in refining and formation of equiaxed ascast structure. There was no evidence of entrapped eutectic within the primary a-Al particles as one of the advantages of SEED slurry-on-demand technology.The reduction of pouring temperature down to liquidus point, 615°C, improved the flow characteristics of the billets. The calculated viscosity for the billets with globular primary a-Al particles are almost three orders of...

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Effect of Foaming Condition on Cell Morphology of Superplastic Zn-22Al Alloy Foams Manufactured through Melt Foaming Process

健治¹,

Kitazono²

2013

J. Japan Inst. Metals and Materials

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Closed cell superplastic Zn 22Al eutectoid alloy foams were manufactured through the melt foaming process using titanium hydride powder as a foaming agent. Foaming tests were carried out under different foaming temperatures, times and additive amounts of foaming agent. Maximum porosity of 75 and small pore diameter were obtained during the temperature range of semi solid condition from 738 753 K. This is because of increased melt viscosity. Though the small amount of the foaming agent is effective to decrease the pore diameter, the porosity becomes low. Cell morphology of the present Zn 22Al alloy foam is identical to conventional aluminum foams. Semi solid condition of Zn 22Al foam has an advantage over increasing melt viscosity on manufacturing of metal foam.

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Effect of Chemical Composition on Apparent Viscosity of Semi-solid Metals

Cited by 5 publications

References 8 publications

The implication of rheology in semi-solid metal processes: An overview

The implication of rheology in semi-solid metal processes: An overview

rheological behavior of semi-solid A356 alloy /

Effect of Foaming Condition on Cell Morphology of Superplastic Zn-22Al Alloy Foams Manufactured through Melt Foaming Process

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