Rapid Solidification Processing: Melt Spinning of Al-High Si Alloys

Rapid solidification processing is a technique used for refining the primary silicon and seems to be the most promising technique for the production of high Si Al-Si alloys (i.e. Si content greater than 17 wt.%). There are number of routes which can be used to produce rapid solidification, including spray methods, weld methods, and chill methods. Of these, melt spinning is the most widely used industrially due to its high cooling rate and the ability to process large volumes of materials. This paper summarizes melt spinning and rapid solidification, highlighting a potential production route for aluminium-high silicon alloys involving melt spinning followed by hot isostatic processing.

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Hardness of Rapidly Solidified Al-High Si Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.476-478.2476 ◽

2012 ◽

Vol 476-478 ◽

pp. 2476-2480 ◽

Cited By ~ 1

Author(s):

F. Alshmri ◽

H.V. Atkinson

Keyword(s):

Rapid Solidification ◽

Melt Spinning ◽

High Wear Resistance ◽

Solidification Processing ◽

High Corrosion Resistance ◽

Silicon Alloys ◽

Low Thermal Expansion ◽

High Silicon ◽

Si Content ◽

Rapidly Solidified

Abstract. Aluminum high silicon alloys have concerned many researchers due to their high wear resistance, lightness, high corrosion resistance and low thermal expansion. Casting of high silicon Al-Si alloys (i.e. Si content greater than 17 wt.%) will generate large degrees of segregation and coarse microstructures due to the low rates of solidification. The problems associated with ingot casting of hypereutectic Al-Si alloys (i.e. segregation, coarse microstructures and porosity) may be overcome by rapid solidification processing such as spray, weld, and chill methods (e.g. melt spinning). The alloys under consideration here contain Al, Si, Zr, Cu, Mg, Fe and Ni. These alloys were produced by rapid solidification i.e. melt spinning. The aim of this paper is to characterise the hardness of material produced by rapid solidification at various stages of production. Several alloy variants were examined and relate the hardness to the microstructure. Piston A390 made by casting was examined for comparison.

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Microstructural Morphology and Phase Structure of Rapidly Solidified Hypereutectic Al-Si Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.139 ◽

2009 ◽

Vol 79-82 ◽

pp. 139-142

Author(s):

Ai Qin Wang ◽

Ji Wen Li ◽

Jing Pei Xie ◽

Wen Yan Wang

Keyword(s):

Melt Spinning ◽

Primary Silicon ◽

Nucleation And Growth ◽

Rapid Solidification Processing ◽

Solidification Processing ◽

Α Phase ◽

Equilibrium Solidification ◽

Microstructural Morphology ◽

Rapidly Solidified ◽

Morphology Characteristics

In the present work, rapidly solidified hypereutectic Al-Si-Cu-Mg alloys strips was prepared by single roller melt-spinning method. The microstructures, phase and morphology characteristics of the resultant strips were characterized by means of SEM, TEM and XRD technique. The results show that the grains are refined after rapid solidification processing, and the micro-nanocrystals are formed. Compared with equilibrium solidification, the microstructures are changed obviously. The nucleation and growth of primary silicon are suppressed and primary silicon can not deposited, meanwhile, α-Al phase is nucleated which prior to eutectic. Therefore, the microstructures become into the metastable state. The microstructures of the strips are composed of primary micro-nanostructure α phase and feather-needles-like (α+Si) eutectic which set in the α phase. The mechanism of the formation for microstructures of melt-spinning Al–Si alloy have also been discussed.

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Centrifuge Melt Spinning Improves Rapid Solidification Processing

Materials and Processing Report ◽

10.1080/08871949.1989.11752221 ◽

1989 ◽

Vol 3 (10) ◽

pp. 2-3

Author(s):

J. Baram

Keyword(s):

Rapid Solidification ◽

Melt Spinning ◽

Rapid Solidification Processing ◽

Solidification Processing

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Some Fundamental Considerations During Rapid Solidification Processing

MRS Proceedings ◽

10.1557/proc-28-21 ◽

1983 ◽

Vol 28 ◽

Cited By ~ 2

Author(s):

V. Laxmanan

Keyword(s):

Cooling Rate ◽

Rapid Solidification ◽

Stability Criterion ◽

Thermal Gradient ◽

Absolute Stability ◽

Melt Spinning ◽

Rapid Solidification Processing ◽

Dendritic Solidification ◽

Solidification Processing ◽

The Third

ABSTRACTThree estimates of the solidification rates required to obtain a fully homogeneous structure during rapid solidification processing (RSP) have been made. One is given by the “absolute stability” criterion and another obtained from a new analysis for dendritic solidification. The third estimate, also derived from the above analysis, requires that “hypercooled” conditions be maintained after nucleation. A mechanism for the formation of “featureless” segregation-free zones during melt spinning and atomization processes is suggested and expressions for the critical cooling rate and thermal gradient required to produce such structures have been obtained.

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Microstructural Characterization of Rapidly Solidified Al-High Si Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.328-330.1545 ◽

2011 ◽

Vol 328-330 ◽

pp. 1545-1551 ◽

Cited By ~ 3

Author(s):

Helen V. Atkinson ◽

Faraj Alshmri ◽

S.V. Hainsworth ◽

S.D.A. Lawes

Keyword(s):

Melt Spinning ◽

Microstructural Characterization ◽

Primary Silicon ◽

Raw Material ◽

Aluminium Content ◽

Solidification Processing ◽

Silicon Alloys ◽

Wheel Side ◽

Rapidly Solidified

Aluminium silicon alloys are the most used raw material for automotive applications. One of the main limitations on using aluminium high silicon alloys is the formation of coarse brittle phases under conventional solidification conditions. However, rapid solidification processing (RS) (for example, through melt spinning) is very effective in limiting the coarsening of primary silicon due to the high cooling rate. In the present work, characterisation of the material at the first stage of production as melt-spun ribbon and flake has been carried out. The microstructures show typical characteristics of a ‘featureless zone’ on the wheel-side and coarser microstructures on the air-side, with clusters of silicon particles evident. At high magnification, on the wheel-side, TEM and FEGSEM reveal local variations in the silicon and aluminium content (although on average there is no macrosegregation from the wheel-side to the air-side during solidification). In FEGSEM, the ‘rosette-structure’ also displays local variations in Al, Si, Fe, Cu and Ni over a scale of a few microns.

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