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.

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.

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.

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.

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.

Microstructural analysis for Sn-Bi-Sb-In alloy prepared by rapid solidification

2016 ◽  
Vol 12 (2) ◽  
pp. 4244-4254
Author(s):  
Sara Mosaad Mahlab ◽  
Mustafa Kamal ◽  
Abd El-Raouf Mansour
Keyword(s):  
Electron Microscopy ◽  
Microstructure Evolution ◽  
Melt Spinning ◽  
Vickers Microhardness ◽  
Microstructural Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rapidly Solidified ◽  
Melt Spinning Technique ◽  
Scanning Electron

In the present study, Sn70-X at.% -Bi15 at.% -Sb15 at.%- Inx at.%  alloy ( x= 0, 2, 4, 6),  were prepared by melt spinning technique. Optical microscopy, scanning electron microscopy combined with energy dispersive X-ray analysis (SEM-EDX), X-ray diffraction analysis (XRD), and Vickers microhardness (Hv); were used to characterize the phase transformation and the microstructure evolution. The results contribute to the understanding of the microstructure evolution in alloys of the type prepared by melt spinning technique. This work reports on a comparative study of the rapidly solidified, in order to compare the microhardness and microstructural analysis. 

The Effects of La on Rapidly Solidified Al – 66 at.% NI

1994 ◽  
Vol 360 ◽  
Author(s):  
Baode Sun ◽  
Yaohe Zhou ◽  
Hul Lin ◽  
Dongllang Lin
Keyword(s):  
Grain Boundaries ◽  
Melt Spinning ◽  
Single Phase ◽  
Enhancement Mechanism ◽  
Microstructural Morphology ◽  
Rapidly Solidified ◽  
B2 Structure

AbstractThis paper investigates the microstructure and ductility of Al - 66 at.% Ni by means of melt spinning technology combined with La microalloying. It shows that the Al - 66 at.% Ni without La exhibits coarse equiaxed martensite grains with Ni3Al precipitating at the grain boundaries (GBs). An addition of 0.05 wt.% La suppresses the precipitation of Ni3Al and a microstructure of complete martensite is obtained. When the amount of La is 0.2∼0.8 wt.%, a “supersaturated” single phase of B2 structure NiAl results. The elongation of Al - 66 at.% Ni without La is only 0.8%. When 0.05, 0.2, and 0.8 (wt.%) La are added to the alloy, their elongations can be as high as 2.6, 3.0, and 3.2% respectively. This shows that the elongation increases with increasing La content. The microstructural morphology and the ductility enhancement mechanism are 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.

Spherulite Structures in a Melt Spun Fe-Ni Austenitic Steel

1985 ◽  
Vol 43 ◽  
pp. 52-53
Author(s):  
G. M. Michal ◽  
T. K. Glasgow ◽  
T. J. Moore
Keyword(s):  
Austenitic Steel ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Large Range ◽  
Amorphous Structure ◽  
Nucleation And Growth ◽  
Ni Alloys ◽  
Melt Spun ◽  
Crystal Fibers ◽  
Rapidly Solidified

Large additions of B to Fe-Ni alloys can lead to the formation of an amorphous structure, if the alloy is rapidly cooled from the liquid state to room temperature. Isothermal aging of such structures at elevated temperatures causes crystallization to occur. Commonly such crystallization pro ceeds by the nucleation and growth of spherulites which are spherical crystalline bodies of radiating crystal fibers. Spherulite features were found in the present study in a rapidly solidified alloy that was fully crysstalline as-cast. This alloy was part of a program to develop an austenitic steel for elevated temperature applications by strengthening it with TiB2. The alloy contained a relatively large percentage of B, not to induce an amorphous structure, but only as a consequence of trying to obtain a large volume fracture of TiB2 in the completely processed alloy. The observation of spherulitic features in this alloy is described herein. Utilization of the large range of useful magnifications obtainable in a modern TEM, when a suitably thinned foil is available, was a key element in this analysis.

EM of rapidly solidified permanent magnets

1992 ◽  
Vol 50 (1) ◽  
pp. 198-199
Author(s):  
Raja K. Mishra
Keyword(s):  
Melt Spinning ◽  
Permanent Magnets ◽  
Dark Field Image ◽  
Dark Field ◽  
Maximum Energy ◽  
Quench Rate ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Annular Dark Field ◽  
Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

1990 ◽  
Vol 48 (4) ◽  
pp. 990-991
Author(s):  
Mahesh Chandramouli
Keyword(s):  
Electron Microscope ◽  
Liquid Phase ◽  
Permanent Magnets ◽  
Phase Distribution ◽  
Energy Dispersive Spectrometer ◽  
Nucleation And Growth ◽  
Liquid Phase Sintering ◽  
Domain Wall Energy ◽  
Oxide Phases ◽  
Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

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