The Role of Fe on the Grain Refinement of High Purity Aluminium

The role of Fe on the grain refinement of high purity aluminium (HPAl) was investigated after adding commercial Al-5Ti-1B grain refiner rod. Experimental results show that with a 0.08% Fe addition, the grain structure at chill zone of the HPAl sample changes from coarse to fine equiaxed grains. More importantly, the grain size observed at the centre of the HPAl sample decreased from 500±50µm to 206±30µm. The improvement has been attributed to the interfacial segregation and solute concentration of the Fe at the solid-liquid interface.

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Evolution of the Solidification Microstructure of Rheocast High Purity Aluminium

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.192-193.109 ◽

2012 ◽

Vol 192-193 ◽

pp. 109-115 ◽

Cited By ~ 1

Author(s):

Sarah George ◽

Robert Knutsen

Keyword(s):

High Purity ◽

Liquid Interface ◽

Cellular Growth ◽

Solidification Mode ◽

Purity Aluminium ◽

High Purity Aluminium ◽

Semi Solid ◽

The Stability ◽

Solid Liquid Interface ◽

Solid Liquid

High purity aluminium has been successfully rheocast using the CSIR-RCS system combined with high pressure die casting. Analysis of the as-cast microstructure by SEM and EBSD revealed the presence of in-grain substructures. These morphological features show that the overall growth mode of the globular grains during rheocasting is planar, but the presence of these features indicates that the solidification mode is cellular at some stages during the slurry production process. Cellular solidification is associated with unstable growth at the solid-liquid interface and is initiated and exacerbated by solute gradients between the melt and the newly formed solid. This high purity alloy exhibits the same cellular growth, indicating that even minor solute variations have an effect on the stability of the solid-liquid interface and, hence, the mode of solidification during semi-solid rheocasting.

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The role of electron tunnelling in the development of chemical conversion coatings on high purity aluminium

Corrosion Science ◽

10.1016/0010-938x(93)90022-9 ◽

1993 ◽

Vol 34 (11) ◽

pp. 1853-1857 ◽

Cited By ~ 13

Author(s):

K. Shimizu ◽

G.M. Brown ◽

K. Kobayashi ◽

G.E. Thompson ◽

G.C. Wood

Keyword(s):

High Purity ◽

Chemical Conversion ◽

Conversion Coatings ◽

Electron Tunnelling ◽

Purity Aluminium ◽

High Purity Aluminium

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Grain refinement of high purity aluminium by asymmetric rolling

Materials Science and Technology ◽

10.1179/026708300101507019 ◽

2000 ◽

Vol 16 (10) ◽

pp. 1095-1101 ◽

Cited By ~ 101

Author(s):

Q. Cui ◽

K. Ohori

Keyword(s):

Grain Refinement ◽

High Purity ◽

Asymmetric Rolling ◽

Purity Aluminium ◽

High Purity Aluminium

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Microstructure, Texture and Property Changes of High Purity Aluminium during Accumulative Roll Bonding and Conventional Rolling

Materials Science Forum ◽

10.4028/www.scientific.net/msf.503-504.711 ◽

2006 ◽

Vol 503-504 ◽

pp. 711-716 ◽

Cited By ~ 3

Author(s):

Margarita Slámová ◽

Petr Homola ◽

P. Sláma ◽

Jakub Čížek ◽

Ivan Procházka ◽

...

Keyword(s):

Dislocation Density ◽

Grain Refinement ◽

High Purity ◽

Accumulative Roll Bonding ◽

Cube Texture ◽

Moderate Increase ◽

Roll Bonding ◽

Purity Aluminium ◽

High Purity Aluminium ◽

Conventional Rolling

It is known that the severe plastic deformation (SPD) induced by Accumulative Roll Bonding (ARB) results in more important grain refinement as compared to conventional rolling. Since ARB enables production of large amounts of ultra-fine grained (UFG) materials, its adoption into industrial practice is favoured. The paper presents the results of a study of high purity aluminium processed by ARB and cold rolling. Microstructure changes induced by both methods were studied by light and transmission electron microscopy. Dislocation density and arrangement were assessed by positron annihilation spectroscopy. Strength evolution was estimated by hardness measurements. Texture measurements were performed by X-ray diffraction. ARB processing results in over twofold increase in hardness. Hardness increases significantly after two ARB cycles and it raises only a little or decreases during subsequent cycles. The increase in hardness induced by conventional rolling is smaller. Positron lifetime measurements reveal a substantial increase of dislocation density at the first ARB cycle and a moderate increase or even a decrease at further cycles. The high fraction of positrons trapped at grain-boundary dislocations gives evidence for substantial grain refinement confirmed by TEM examinations. Grain size of 1.2 􀁐m in the rolling plane and as small as of 90 nm in the normal direction is obtained. The rolled samples have a typical rolling texture (􀁅-fibre). The 􀁅- fibre of the sample ARB processed to strain of 2.4 is weaker as compared to its rolled counterpart and it presents through thickness variations. The surface layers do not have any 􀁅-fibre orientations but they have ND-rotated cube texture formed by the shear strains induced by lubricant-free rolling.

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Precipitation Behavior in High-Purity Aluminium Alloys with Trace Elements - The Role of Quenched-in Vacancies

physica status solidi (a) ◽

10.1002/pssa.201800375 ◽

2018 ◽

Vol 215 (24) ◽

pp. 1800375 ◽

Cited By ~ 4

Author(s):

Frank Lotter ◽

Uwe Muehle ◽

Mohamed Elsayed ◽

Alaa M. Ibrahim ◽

Thomas Schubert ◽

...

Keyword(s):

Trace Elements ◽

High Purity ◽

Aluminium Alloys ◽

Precipitation Behavior ◽

Purity Aluminium ◽

High Purity Aluminium

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The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface

Water Science & Technology ◽

10.2166/wst.1999.0336 ◽

1999 ◽

Vol 39 (7) ◽

pp. 91-98 ◽

Cited By ~ 3

Author(s):

Ryan N. Jordan ◽

Eric P. Nichols ◽

Alfred B. Cunningham

Keyword(s):

Mass Transfer ◽

Cell Membrane ◽

Substrate Concentration ◽

Water Interface ◽

Industrial Systems ◽

Solid Liquid Interface ◽

Solid Liquid ◽

Surfactant Sorption

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate concentration that the cell membrane “sees,” (i.e., the “directly bioavailable” pool) as well as (2) the rate of mass transfer from potentially bioavailable (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two processes are discussed. We propose the hypothesis that the sorption of (bio)surfactants at the solid-liquid interface is partially responsible for the increased bioavailability of surface-bound nutrients, and offer this as a basis for suggesting the development of engineered in-situ bioremediation technologies that take advantage of low (bio)surfactant concentrations. In addition, other industrial systems where bioavailability phenomena should be considered are addressed.

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Microstructural Evolutions of 2N Grade Pure Al and 4N Grade High-Purity Al during Friction Stir Welding

Materials ◽

10.3390/ma14133606 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3606

Author(s):

Tomoya Nagira ◽

Xiaochao Liu ◽

Kohasaku Ushioda ◽

Hidetoshi Fujii

Keyword(s):

Friction Stir Welding ◽

Dynamic Recrystallization ◽

Grain Refinement ◽

High Purity ◽

Cube Texture ◽

Grain Structure ◽

Welding Temperature ◽

Friction Stir ◽

Continuous Dynamic Recrystallization ◽

Dislocation Annihilation

The grain refinement mechanisms along the material flow path in pure and high-purity Al were examined, using the marker insert and tool stop action methods, during the rapid cooling friction stir welding using liquid CO2. In pure Al subjected to a low welding temperature of 0.56Tm (Tm: melting point), the resultant microstructure consisted of a mixture of equiaxed and elongated grains, including the subgrains. Discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization are the potential mechanisms of grain refinement. Increasing the welding temperature and Al purity encouraged dynamic recovery, including dislocation annihilation and rearrangement into subgrains, leading to the acceleration of CDRX and inhibition of DDRX. Both C- and B/-type shear textures were developed in microstructures consisting of equiaxed and elongated grains. In addition, DDRX via high-angle boundary bulging resulted in the development of the 45° rotated cube texture. The B/ shear texture was strengthened for the fine microstructure, where equiaxed recrystallized grains were fully developed through CDRX. In these cases, the texture is closely related to grain structure development.

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