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

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.

Microstructures of Rapidly Solidified Hypereutectic Al-Si Alloy with Low-Titanium Content

2008 ◽  
Vol 575-578 ◽  
pp. 27-31
Author(s):  
Ai Qin Wang ◽  
Jing Pei Xie ◽  
Zhong Xia Liu ◽  
Ji Wen Li ◽  
Wen Yan Wang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Melt Spinning ◽  
Supersaturated Solid Solution ◽  
Primary Silicon ◽  
Titanium Content ◽  
Nucleation And Growth ◽  
Solidification Processing ◽  
Equilibrium Solidification ◽  
Rapidly Solidified ◽  
Morphology Characteristics

In the present work, rapidly solidified alloys strips with Al-0.24Ti and Al-21Si-0.24Ti(in wt.%) were prepared by single roller melt-spinning method. The microstructures, phase and morphology characteristics of the resultant strips were characterized by means of scanning electron microscopy (SEM),transmission electric microscopy (TEM) and XRD technique. The results show that the grains have been refined after rapid solidification processing, and the micro-nanocrystalline grain are formed. The morphology characteristics can be changed. The microstructures of Al-0.24Ti alloys strip are micro-nanostructure α-Al solid solutions which are similar with granular or nodular, the corresponding SAD pattern is rings, it presents characteristic of polycrystal; Compared with equilibrium solidification, the microstructures of hypereutectic Al-Si alloy are changed obviously. They are composed of primary micro-nanostructure α-Al supersaturated solid solution and nanocrystal granular (α+Si) eutectic which set in the supersaturated solid solution. The nucleation and growth of primary silicon are suppressed and primary silicon can not precipitate, meanwhile, α-Al phase is nucleated which prior to eutectic, therefore the microstructures become into the metastable state. The mechanism of the formation for microstructures of melt-spinning alloys has also been discussed.

Microstructural Morphology and Formation Mechanism of Rapidly Solidified Al-21Si Multi-Alloys

2010 ◽  
Vol 146-147 ◽  
pp. 1597-1600
Author(s):  
Ai Qin Wang ◽  
Jing Pei Xie ◽  
Wen Yan Wang ◽  
Ji Wen Li
Keyword(s):  
Melt Spinning ◽  
Primary Silicon ◽  
Nucleation And Growth ◽  
Mechanism Of Formation ◽  
Α Phase ◽  
Conventional Condition ◽  
Microstructural Morphology ◽  
Rapidly Solidified ◽  
Morphology Characteristics ◽  
Scanning Electron

In the present work, rapidly solidified Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys strips was prepared by melt-spinning method. The microstructures, phase and morphology characteristics of the experimental alloy were characterized by means of scanning electron microscopy, transmission electric microscopy. The results show that the microstructures are changed obviously compared with conventional condition. 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. The microstructures of the rapidly solidified alloys are composed of primary micro-nanostructure α phase and feather-needles-like (α+Si) eutectic which set in the α phase. The mechanism of formation for microstructures of melt-spinning Al-Si alloy have also been discussed.

The Metastable Micro-Nanocrystals and Formation Mechanism of Rapidly Solidified Al-21Si Multi-Alloys

2014 ◽  
Vol 636 ◽  
pp. 97-100 ◽  
Author(s):  
Ai Qin Wang ◽  
Hui Hui Han ◽  
Jing Pei Xie ◽  
Ji Wen Li
Keyword(s):  
Formation Mechanism ◽  
Melt Spinning ◽  
Primary Silicon ◽  
Nucleation And Growth ◽  
Microstructure Formation ◽  
Microstructure Morphology ◽  
Alloy Microstructure ◽  
Rapidly Solidified ◽  
Melt Spinning Technique ◽  
Scanning Electron

In the present work, rapidly solidified Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys strips was prepared by melt-spinning technique. The microstructure morphology and phase structures of experimental alloy were characterized by means of scanning electron microscopy (SEM), transmission electric microscopy (TEM) and XRD technique. The results show that the grains were refined and the micro-nanocomposite structural were formed under rapid solidification. The nucleation and growth of primary silicon were suppressed and primary silicon could not deposited, meanwhile, α-Al phase was nucleated which prior to eutectic. The microstructure of the Al-21Si alloy was composed of micro-nanostructured α-Al phase and feather-needles-like eutectic α-Al+β-Si phase. The hypereutectic Al-21Si alloy showed the hypoeutectic microstructure. The rapidly solidified Al-21Si alloy microstructure formation mechanism has also been discussed.

Microstructural Characterization of Rapidly Solidified Al-High Si Alloys

2011 ◽  
Vol 328-330 ◽  
pp. 1545-1551 ◽  
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.

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

2011 ◽  
Vol 383-390 ◽  
pp. 1740-1746 ◽  
Author(s):  
Faraj Alshmri
Keyword(s):  
Rapid Solidification ◽  
Melt Spinning ◽  
Primary Silicon ◽  
Rapid Solidification Processing ◽  
Promising Technique ◽  
Solidification Processing ◽  
Silicon Alloys ◽  
Production Route ◽  
Hot Isostatic Processing ◽  
Si Content

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.

The Microstructure Characteristics and Wear Resistance of Rapidly Solidified Hypereutectic Al-Si Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 986-989 ◽  
Author(s):  
Ji Wen Li ◽  
Ai Qin Wang ◽  
Jing Pei Xie ◽  
Wen Yan Wang ◽  
Luo Li Li
Keyword(s):  
Wear Resistance ◽  
Composite Structures ◽  
Melt Spinning ◽  
Primary Silicon ◽  
Nano Composite ◽  
Casting Alloys ◽  
Microstructure Morphology ◽  
Rapidly Solidified ◽  
Morphology Characteristics ◽  
Melt Spinning Technique

Rapidly solidified hypereutectic Al-21Si was prepared by the single roller melt-spinning technique. The microstructure morphology characteristics and phase structures of the alloy were characterized using SEM, TEM and XRD technique. The results showed that the grains were refined and the micro-nano composite structures were formed under rapid solidification. The microstructure of the Al-21Si alloy was composed of micro-nanostructured α-Al phase and feather-needle-like eutectic α-Al+β-Si phase. The α-Al phase was the leading phase in the eutectic α+Si phase. The nucleation and growth of primary silicon are suppressed and primary silicon could not be precipitated. The hypereutectic Al-21Si alloy showed the hypoeutectic solidification microstructure. Wear resistance was improved obviously when the rapidly solidified and was five times higher than that of the traditional casting alloys.

The structure of rapidly solidified Fe-Ni-Mo-Co-B ribbons

1989 ◽  
Vol 47 ◽  
pp. 290-291
Author(s):  
D. M. Vanderwalker
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Lattice Parameter ◽  
Rapid Solidification Processing ◽  
Solidification Processing ◽  
Casting Technique ◽  
Transmission Electron ◽  
Structural Applications ◽  
Melt Spun ◽  
Rapidly Solidified

Fundamental aspects of solidification can be examined by experimentation in rapid solidification processing. The structure produced depends on parameters such as cooling rate, degree of undercooling, heat flow, and growth rate. Rapidly solidified iron base alloys are being developed for structural applications.RSR I Fe-19.7Mo-14.4Ni-7.3Co-1.9Bwt % and RSR II Fe-15.0Ni-11.1Mo-7.4Co-0.84B wt% ribbons were melt spun by a jet casting technique. RSR I ribbons were annealed for one hour at 816°C.Specimens were prepared for transmission electron microscopy by punching 3 mm discs from ribbons and electropolishing in a methanol 5% perchloric acid solution.The TEM was performed on the JEM 200CX electron microscope.As solidified RSR I was found to be canposed of fine (7nm) polycrystalline α-Fe. There is evidence for the presence of Ni Mo and FeB (Fig.1). On annealing, the α-Fe transforms to γ-Fe and FeB2Mo2, with significant grain growth (Fig.2). The as-solidified RSR II contains cellular γ-Fe with fcc-Fe2 3B6 of lattice parameter a=l.067nm at the cell walls (Fig. 3).

Rapidly Solidified Long Range Ordered Alloys

1981 ◽  
Vol 8 ◽  
Author(s):  
E. H. Lee ◽  
C. C. Koch ◽  
C. T. Liu
Keyword(s):  
Long Range ◽  
Cell Structure ◽  
Rapid Solidification Processing ◽  
Microstructural Feature ◽  
Solidification Processing ◽  
Transmission Electron ◽  
Ordered Alloys ◽  
Before And After ◽  
Rapidly Solidified ◽  
Carbide Particles

ABSTRACTThe influence of rapid solidification processing on the microstructure of long-range-ordered alloys in the (Fe,Co,Ni)3 V system has been studied by transmission electron microscopy. The main microstructural feature of the asquenched alloys was a fine cell structure (∼300 nm diameter) decorated with carbide particles. This structure was maintained after annealing treatments which develop the ordered crystal structure. Other features of the microstructures both before and after annealing are presented and discussed.

Some Fundamental Considerations During Rapid Solidification Processing

1983 ◽  
Vol 28 ◽  
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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