Pore formation in cast metals and alloys

Gupta, Anil; Saxena, B K; Tiwari, Shivam; Malhotra, S. L.

doi:10.1007/bf01197634

Cited by 35 publications

(13 citation statements)

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“…As suggested by Campbell [23] , and Gupta et al [24 ] an oxide film can be a potential site for the formation of gas and shrinkage porosity in conventional cast samples. Generally, oxide films present in as-cast Al alloys are there as bifilms, and are easy for gas entrapment between the contacting dry side oxide films [23] .…”

Section: Porositymentioning

confidence: 99%

Solidification Behavior of Intensively Sheared Hypoeutectic Al-Si Alloy Liquid

Kotadia

Babu

Zhang

et al. 2010

Metall Mater Trans A

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Abstract:The effect of the processing temperature on the microstructural and mechanical properties of Al-Si (hypoeutectic) alloys solidified from intensively sheared liquid metal has been investigated systematically. Intensive shearing gives a significant refinement in grain size and intermetallic particle size. It is also observed that the morphology of intermetallics, defect bands and microscopic defects in high pressure die cast components are affected by intensive shearing the liquid metal. We attempt to discuss the possible mechanism for these effects.

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Section: Porositymentioning

confidence: 99%

Solidification Behavior of Intensively Sheared Hypoeutectic Al-Si Alloy Liquid

Kotadia

Babu

Zhang

et al. 2010

Metall Mater Trans A

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“…[8,12] Some conflicting research has shown that sodium additions actually result in a decrease in porosity, [8] or alternatively, a decrease of the required riser size to avoid porosity formation. [14] It is generally accepted that the nucleation and growth of porosity in a solidifying casting occurs when the following pressure imbalance is present: [12,15,16] [1]…”

Section: Introductionmentioning

confidence: 99%

Modification-related porosity formation in hypoeutectic aluminum-silicon alloys

McDonald

Dahle

Taylor

et al. 2004

Metall Mater Trans B

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A series of aluminum-10 wt pct silicon castings were produced in sand molds to investigate the effect of modification on porosity formation. Modification with individual additions of either strontium or sodium resulted in a statistically significant increase in the level of porosity compared to unmodified castings. The increase in porosity with modification is due to the presence of numerous dispersed pores, which were absent in the unmodified casting. It is proposed that these pores form as a result of differences in size of the aluminum-silicon eutectic grains between unmodified and modified alloys. A geometric model is developed to show how the size of eutectic grains can influence the amount and distribution of porosity. Unlike traditional feeding-based models, which incorporate the effect of microstructure on permeability, this model considers what happens when liquid is isolated from the riser and can no longer flow. This simple "isolation" model complements rather than contradicts existing theories on modification-related porosity formation and should be considered in the development of future comprehensive models.

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“…This prevents the gases from being diffused into the liquid Zn during the solidification process and, as a result, no voids are formed. 11,12 Note also that the pressure accelerates the infiltration of Zn into the via holes.…”

Section: Resultsmentioning

confidence: 96%

“…The trapping of voids in the vias can be explained by a mechanism of pore formation. 11,12 During the reflow process, the liquid Zn flows into the via holes and the Zn vapor acts as a barrier against the surrounding gases. Nonetheless, the surrounding gases are diffused into the liquid Zn during the cooling process because, in accordance with the Clausius-Clapeyron relation, there is a significant reduction in the vapor pressure of Zn.…”

Section: Resultsmentioning

confidence: 99%

Zinc and Tin-Zinc Via-Filling for the Formation of Through-Silicon Vias in a System-in-Package

Jee

Park

et al. 2009

Journal of Elec Materi

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Microvias of 50 lm diameter in a Si chip were filled with Zn or Sn-Zn to form through-silicon vias by means of an electroplating/reflow process or a dipping method. In the case of the electroplating/reflow process, Zn was electroplated on a Cu seed layer in via holes, and a reflow was then performed to fill the via holes with the electroplated Zn. In the case of the dipping method, Zn via-filling and Sn-Zn via-filling were performed by dipping a via hole specimen into a molten bath of Zn or Sn-Zn. A filling pressure greater than 3 MPa during the via-filling is essential for ensuring that the via holes are completely filled with Zn or Sn-Zn and for preventing voids from being trapped in the vias. The melting temperature and electrical conductivity of the Sn-Zn alloys increases almost linearly with the content of Zn, implying that the thermal and electrical properties of the Sn-Zn vias can be easily controlled by varying the composition of the Sn-Zn vias. A chip-stack specimen was fabricated by flip-chip bonding of three chips with Zn vias.

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Pore formation in cast metals and alloys

Cited by 35 publications

References 0 publications

Solidification Behavior of Intensively Sheared Hypoeutectic Al-Si Alloy Liquid

Solidification Behavior of Intensively Sheared Hypoeutectic Al-Si Alloy Liquid

Modification-related porosity formation in hypoeutectic aluminum-silicon alloys

Zinc and Tin-Zinc Via-Filling for the Formation of Through-Silicon Vias in a System-in-Package

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