Grain refining of aluminium and its alloys using inoculants

McCartney, D.G.

doi:10.1179/imr.1989.34.1.247

Cited by 616 publications

(301 citation statements)

References 25 publications

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“…[19] These metastable particles are isostructural to, and exhibit a small lattice parameter mismatch with, the a-Al solid solution, and therefore act as efficient heterogeneous nucleants during solidification of a-Al. The resulting grain refinement in cast alloys is frequently exploited industrially by Ti additions to Al [19][20][21][22] and has also been observed in Al-Zr [19,23,24] and Al-Hf [25][26][27] alloys when primary precipitation of Al 3 M (L1 2 ) occurs. The refined grain size, however, is undesirable for applications where creep resistance is required.…”

Section: The Group 4 Transition Metals (Ti Zr or Hf)mentioning

confidence: 99%

“…As discussed, minor additions of Ti are used to refine the grain structure in commercial aluminum alloys, where primary Al 3 Ti precipitates act as heterogeneous nuclei during solidification of the melt. [19][20][21][22] A solid-state counterpart to this grain refinement effect is realized when dilute additions of Zr are added to commercial wrought alloys as recrystallization inhibitors. [82][83][84][85] Small (20 to 30 nm) coherent Al 3 Zr (L1 2 ) precipitates, formed during post-solidification aging, are effective barriers to grain-boundary migration.…”

Section: E Common Industrial Uses Of Ti and Zr Additions To Almentioning

confidence: 99%

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Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Knipling

Dunand

Seidman

2007

Metall Mater Trans A

177

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Two conventionally solidified Al-0.2Ti alloys (with 0.18 and 0.22 at. pct Ti) exhibit no hardening after aging up to 3200 hours at 375°C or 425°C. This is due to the absence of Al 3 Ti precipitation, as confirmed by electron microscopy and electrical conductivity measurements. By contrast, an Al-0.2Zr alloy (with 0.19 at. pct Zr) displays strong age hardening at both temperatures due to precipitation of Al 3 Zr (L1 2 ) within Zr-enriched dendritic regions. This discrepancy between the two alloys is explained within the context of the equilibrium phase diagrams: (1) the disparity in solid and liquid solubilities of Ti in a-Al is much greater than that of Zr in a-Al; and (2) the relatively small liquid solubility of Ti in a-Al limits the amount of solute retained in solid solution during solidification, while the comparatively high solid solubility reduces the supersaturation effecting precipitation during post-solidification aging. The lattice parameter mismatch of Al 3 Ti (L1 2 ) with a-Al is also larger than that of Al 3 Zr (L1 2 ), further hindering nucleation of Al 3 Ti. Classical nucleation theory indicates that the minimum solute supersaturation required to overcome the elastic strain energy of Al 3 Ti nuclei cannot be obtained during conventional solidification of Al-Ti alloys (unlike for Al-Zr alloys), thus explaining the absence of Al 3 Ti precipitation and the presence of Al 3 Zr precipitation.

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Section: The Group 4 Transition Metals (Ti Zr or Hf)mentioning

confidence: 99%

Section: E Common Industrial Uses Of Ti and Zr Additions To Almentioning

confidence: 99%

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Knipling

Dunand

Seidman

2007

Metall Mater Trans A

177

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“…It is well known that the content of alloying elements has a significant impact on the size and shape of the primary grains of α(Al) dendrites and even on the transformation from columnar to equiaxed crystallization (exogenous -endogenous) [8][9][10][11][12]. Small secondary dendrite arm spacing (SDAS) and less dendrite branching leads to a more-homogeneous structure.…”

Section: Introductionmentioning

confidence: 99%

The effect of nickel on shaping the structure of Al-Cu-Mn alloys

Górny

Sikora²,

Tyrała

et al. 2017

jcme

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This study investigated the effect of nickel on shaping the structure of aluminum alloys of the Al-Cu-Mn type in the "as-cast" condition and after heat treatment according to the T6 procedure. The aluminum alloys of type Al-5%Cu-1%Mn, containing nickel in a range of up to 1.9%, were taken into consideration in this work. Experiments were carried out for thin-walled thickness casting (g = 5 mm) and for reference casting with a wall thickness of g = 35 mm. Metallographic investigations of both the macro-and micro-structure were conducted to estimate the secondary dendrite arm spacing (SDAS), average diameter (dav) of the primary α (Al) grains, and surface fraction of the interdendritic phases (f). Moreover, the degree of dissolution of these interdendritic phases during the solution treatment process was determined. An SEM-EDS analysis was conducted, from which it follows that the addition of nickel at the level of 0.5% changes the un-dissolved particles from a needle-like β-Fe shape to blocky and coagulated. Higher additions of nickel starting from 0.88%) give rise to as many as four phases with higher copper content, the deficit of which results in the smaller strengthening effect of α (Al) dendrites.

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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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Grain refining of aluminium and its alloys using inoculants

Cited by 616 publications

References 25 publications

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

The effect of nickel on shaping the structure of Al-Cu-Mn alloys

Assessment of Mechanism of Pore Formation in Directionally Solidified A356 Alloy

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