Investigation of columnar–equiaxed transition and equiaxed growth of aluminium based alloys by X-ray radiography

Reinhart, Gunther; Mangelinck‐Noël, Nathalie; Nguyen-Thi, Henri; Schenk, Thomas; Gastaldi, J.; Billia, B.; Pino, Pablo del; Härtwig, J.; Baruchel, J.

doi:10.1016/j.msea.2005.08.197

Cited by 103 publications

(63 citation statements)

References 14 publications

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“…This is consistent with numerical prediction: conditions for dendrite arm fragmentation by dissolution are satisfied in Al-7 wt% Si but not in Al-3.5 wt% Ni solidification. After fragmentation, the dendrite fragments are likely to settle down and rotate due to gravity, because the density of dendrites (solid) is larger than the melt (Reinhart et al, 2005). This would result in different orientations of dendrite arms exhibiting different colors after anodization treatment, as it is observed for Al-7 wt% Si.…”

Section: Experimental Solidification Resultsmentioning

confidence: 99%

Comparative study of the influence of natural convection on directional solidification of Al–3.5wt% Ni and Al–7wt% Si alloys

Bin

Jung

Mangelinck‐Noël

et al. 2008

Advances in Space Research

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We present numerical simulations of thermosolutal convection for directional solidification of Al-3.5 wt% Ni and Al-7 wt% Si. Numerical results predict that fragmentation of dendrite arms resulting from dissolution could be favored in Al-7 wt% Si, but not in Al-3.5 wt% Ni. Corresponding experiments are in qualitative agreement with the numerical predictions. Distinguishing the two fragmentation mechanisms, namely dissolution and remelting, is critical during experiments on earth, when fluid flow is dominant.

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Section: Experimental Solidification Resultsmentioning

confidence: 99%

Comparative study of the influence of natural convection on directional solidification of Al–3.5wt% Ni and Al–7wt% Si alloys

Bin

Jung

Mangelinck‐Noël

et al. 2008

Advances in Space Research

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“…Depending on the application, one type of grain is preferred and thus favoured, e.g. equiaxed grains in car engines and columnar grains in turbine blades as reported by Reinhart et al 1 and McFadden et al…”

Section: Introductionmentioning

confidence: 96%

The columnar to equiaxed transition of horizontal unsteady-state directionally solidified Al-Si alloys

et al. 2014

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Experiments were conducted to investigate the influence of thermal parameters on the columnar to equiaxed transition during the horizontal unsteady-state directional solidification of Al-Si alloys. The parameters analyzed include the heat transfer coefficients, growth rates, cooling rates, temperature gradients and composition. A combined theoretical and experimental approach is developed to determine the solidification thermal variables considered. The increasing solute content in Al-Si alloys was not found to affect significantly the experimental position of the CET which occurred for cooling rates in the range between 0.35 and 0.64 K/s for any of three alloy compositions examined. A comparative analysis between the results of this work and those from the literature proposed to analyze the CET during upward vertical solidification of Al-Si alloys is reported and the results have shown that the end of the columnar region during horizontal directional solidification is abbreviated as a result of about six times higher thermal gradient than that verified during upward unidirectional solidification of alloys investigated.

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“…Large risers, wide thickness, insulating sleeves and chills can be used to achieve such conditions [4]. The physical mechanism of columnar-to-equiaxed transition (CET) during directional solidification have been considered as the critical point during these studies [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Assessment of Mechanism of Pore Formation in Directionally Solidified A356 Alloy

Uludağ

Dışpınar

2017

Archives of Foundry Engineering

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It is well-known that the better the control of the liquid aluminium allows obtaining of better properties. One of the most important defects that is held responsible for lower properties has been the presence of porosity. Porosity has always been associated with the amount of dissolved hydrogen in the liquid. However, it was shown that hydrogen was not the major source but only a contributor the porosity. The most important defect that causes porosity is the presence of bifilms. These defects are surface entrained mainly due to turbulence and uncontrolled melt transfer. In this work, a cylindrical mould was designed (Ø30 x 300 mm) both from sand and die. Moulds were produced both from sand and die. Water cooled copper chill was placed at the bottom of the mould in order to generate a directional solidification. After the melt was prepared, prior to casting of the DC cast samples, reduced pressure test sample was taken to measure the melt quality (i.e. bifilm index). The cast parts were then sectioned into regions and longitudinal and transverse areas were investigated metallographically. Pore size, shape and distribution was measured by image analysis. The formation of porosity was evaluated by means of bifilm content, size and distribution in A356 alloy.

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Investigation of columnar–equiaxed transition and equiaxed growth of aluminium based alloys by X-ray radiography

Cited by 103 publications

References 14 publications

Comparative study of the influence of natural convection on directional solidification of Al–3.5wt% Ni and Al–7wt% Si alloys

Comparative study of the influence of natural convection on directional solidification of Al–3.5wt% Ni and Al–7wt% Si alloys

The columnar to equiaxed transition of horizontal unsteady-state directionally solidified Al-Si alloys

Assessment of Mechanism of Pore Formation in Directionally Solidified A356 Alloy

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