scholarly journals Grain refinement of commercially pure aluminum with addition of Ti and Zr elements based on crystallography orientation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhongwei Chen ◽  
Kang Yan
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Pure Aluminum ◽  
Al Alloys ◽  
Orientation Relationships ◽  
Grain Refiner ◽  
Heterogeneous Nucleation Site ◽  
Edge Matching ◽  
Commercially Pure ◽  
Al Matrix

Abstract The edge-to-edge matching (E2EM) model and electron back-scatter diffraction (EBSD) technique are used to explore the grain refinement mechanism of commercially pure Al through the addition of Ti and Zr elements. EBSD results show that there are favorable crystallography orientation relationships (ORs) between both Al3Ti and Al3Zr particles with α-Al matrix. Due to these ORs Al3Ti and Al3Zr particles act as the heterogeneous nucleation site during solidification nucleation of Al–Ti and Al–Zr alloys, respectively. Furthermore, both Al3Ti and Al3Zr particles have small values of interplanar spacing mismatch and interatomic spacing misfit with respect to α-Al matrix by using E2EM. It shows that micro-addition of Ti and Zr element is efficient heterogeneous nucleation refiner in commercial purity Al or Al alloys. Besides, there may be some other mechanisms in grain refinement of Al alloys with addition of Ti grain refiner.

An Investigation on Grain Refinement Mechanism of Master Alloys Al-Ti, Al-TiC and Al-Ti-C Toward Pure Aluminum

2013 ◽  
Vol 652-654 ◽  
pp. 1072-1075 ◽  
Author(s):  
Wan Wu Ding ◽  
Jiang Tao Zhu ◽  
Wen Jun Zhao ◽  
Tian Dong Xia
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Pure Aluminum ◽  
Grain Refining ◽  
Nucleation Effect ◽  
Commercially Pure ◽  
Master Alloys ◽  
Refinement Mechanism ◽  
Heat Preservation

The grain refining effects of Al-Ti, Al-TiC and Al-Ti-C master alloys on commercially pure aluminum were compared, and the grain refinement mechanism of TiAl3 and TiC among master alloys was discussed. The results show that: the grain refinement of the master alloys Al-TiC and Al-Ti toward pure aluminum mainly stems from the heterogeneous nucleation role of TiC and TiAl3 particles, but with the extension of heat preservation time of fused mass, its role of heterogeneous nucleation will decline due to dissolution of TiAl3 and aggregation and precipitation of TiC. The preferable grain refinement effects of Al-Ti-C master alloys toward pure aluminum are mainly due to the fact that when TiAl3 and TiC particles are acted commonly as heterogeneous nucleation particles, the heterogeneous nucleation effect of TiC particles will be enhanced because of the presence of TiAl3.

Orientation Studies of α-Al(Fe,Mn)Si Dispersoids in 3xxx Al Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 39-44 ◽  
Author(s):  
Astrid Marie Flattum Muggerud ◽  
Yan Jun Li ◽  
Randi Holmestad
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Orientation Relationship ◽  
Aluminum Matrix ◽  
Al Alloys ◽  
Orientation Relationships ◽  
The Matrix ◽  
The Common ◽  
Habit Planes ◽  
Al Matrix

Dispersoids are important in 3xxx Al alloys, influencing mechanical properties, texture and recrystallization. In this work α-Al (Fe,Mn)Si dispersoids have been studied after low temperature homogenisation. The common orientation relationship between dispersoids and Al matrix has been reported in earlier studies. Here a systematic study on the orientation relationship and its exceptions is presented. It is found that most of the dispersoids follow the common orientation relationship, [1-1 1] α //[1-1 1]Al , (5-2 -7 ) α //(0 1 1)Al . Here the dispersoids are semi coherent with the Aluminum matrix. Different morphologies and habit planes are possible. Deviations from the most commonly observed orientation relationships are presented and discussed, to underline the complexity of the phase and its relation to the matrix.

Theoretical and Practical Considerations of Grain Refinement of Mg-Al Alloys

2005 ◽  
Vol 488-489 ◽  
pp. 299-302 ◽  
Author(s):  
L. Lu ◽  
Arne K. Dahle ◽  
John A. Taylor ◽  
David H. StJohn
Keyword(s):  
Grain Refinement ◽  
Magnesium Alloys ◽  
Al Alloys ◽  
Experimental Results ◽  
Grain Refiner ◽  
Carbon Based

The fundamentals of grain refinement are reviewed with particular focus on magnesium alloys. This is followed by considerations of the theoretical and practical aspects of grain refinement of Mg-Al alloys by carbon-based grain refiners. Finally, experimental results using Al4C3 as a potential grain refiner are presented and discussed.

Eco-Friendly Grain Refinement for A3003 Alloy

2009 ◽  
Vol 620-622 ◽  
pp. 89-92
Author(s):  
Hoon Cho ◽  
Jae Hong Ha ◽  
Byoung Soo Lee ◽  
Sung Ho Chang ◽  
Je Sik Shin
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Grain Growth ◽  
Heterogeneous Nucleation ◽  
Aluminum Matrix ◽  
Graphite Crucible ◽  
Holding Time ◽  
Ti Alloy ◽  
Grain Refiner ◽  
Prolonged Holding

Eco-friendly grain refinement of A3003 alloy was studied by addition of non-toxic Al-Ti alloy because of toxic-fluorine in Al-Ti-B alloys which used as a representative grain refiner for aluminum and its alloys. TiAl3 phase in Al-Ti alloy bring to decrease grain size of A3003 alloy. But, grain growth occurred with prolonged holding time due to the solution of Ti into aluminum matrix. In contrast, lasting grain refinement of A3003 alloy was occurred in graphite crucible. It can be mentioned that carbon comes from graphite crucible was combined with Ti solute in aluminum melt and then TiC acts as a heterogeneous nucleation for A3003 alloy.

Effect of Zirconium Addition on Welding of Aluminum Grain Refined by Titanium

2012 ◽  
Vol 510-511 ◽  
pp. 356-363 ◽  
Author(s):  
A.I.O. Zaid
Keyword(s):  
Pure Aluminum ◽  
Research Work ◽  
Welding Process ◽  
Columnar Structure ◽  
Constant Current ◽  
Grain Refiner ◽  
Metallographic Examination ◽  
Weight Percentage ◽  
Commercially Pure ◽  
Zirconium Addition

Aluminum and its alloys solidify in large grains columnar structure which tends to reduce their mechanical behaviour and surface quality. Therefore, they are industrially grain refined by titanium or titanium + boron. Furthermore, aluminum oxidizes in ordinary atmosphere which makes its weldability difficult and weak. Therefore, it is anticipated that the effect of addition of zirconium at a weight percentages of 0.1% (which proved to be an effective grain refiner on the weldability of aluminum grain refined by Ti) is worthwhile investigating. This formed the objective of this research work. In this paper, the effect of zirconium addition at a weight percentage of 0.1%, which corresponds to the peritctic limit on the aluminum-zirconium phase diagram, on the weldability of aluminum grain refined by Ti is investigated. Rolled sheets of commercially pure aluminum, Al grain refined Ti of 3 mm thickness were welded together using Gas Tungsten Arc Welding method (GTAW), formerly known as TIG. A constant air gap was maintained at a constant current level, 30 ampere AC, was used because it removes the oxides of the welding process under the same process parameters. Metallographic examination of weldments of the different combinations of aluminum and its microalloys at the heat affected zone, HAZ, and base metal was carried out and examined for width, porosity, cracks and microhardness. It was found that grain refining of commercially pure aluminum by Ti resulted in enhancement of its weldability. Similarly, addition of zirconium to Al grain refined by Ti resulted in further enhancement of the weldment. Photomicrographs of the HAZ regions are presented and discussed.

Influence of a Novel Master Alloy Addition on the Grain Refinement of Al-Si Cast Alloys

2013 ◽  
Vol 765 ◽  
pp. 311-315 ◽  
Author(s):  
Leandro Bolzoni ◽  
Magdalena Nowak ◽  
N. Hari Babu
Keyword(s):  
Grain Refinement ◽  
Master Alloy ◽  
Intermetallic Phases ◽  
Al Alloys ◽  
Grain Structure ◽  
Grain Refiner ◽  
Casting Alloys ◽  
Alloy Addition ◽  
Cast Alloys ◽  
The Impact

The grain refinement practice using Ti based chemical additions is well established for wrought Al alloys, especially in the last few decades. In the case of Al-Si casting alloys the practice of adding grain refiners and the impact on castability is not well established in industries. The main reason is the chemical instability of conventionally known Ti based grain refiner which reacts with silicon forming intermetallic phases. Recently, researchers at Brunel University have identified a novel chemical composition that can refine the grain structure of Al-Si alloys in an effective way. Over the last year, this novel grain refiner in the form of master alloy was developed and tested in various Al-Si cast alloys that are commonly used in industry. Significant grain refinement is obtained when the master alloy is added to the liquid metal prior to casting. Moreover, the grain size of the Al-Si cast alloys is observed to be less sensitive to cooling rate when the master alloy is added. In this work, the influence of addition of the master alloy on microstructural evolution of various Al-Si alloys cast under various cooling rates is presented.

Crystallographic study of grain refinement of Al by Nb addition

2014 ◽  
Vol 47 (2) ◽  
pp. 770-779 ◽  
Author(s):  
Feng Wang ◽  
Dong Qiu ◽  
Zhi-Lin Liu ◽  
John A. Taylor ◽  
Mark A. Easton ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Refinement ◽  
Electron Backscatter Diffraction ◽  
Point Of View ◽  
Orientation Relationships ◽  
Matching Model ◽  
X Ray ◽  
Edge Matching ◽  
Transmission Electron ◽  
Backscatter Diffraction

The grain refinement of Al by the addition of a small amount of peritectic-forming solute, Nb, has been studied from the crystallographic point of view. Combining the observations of optical microscopy and scanning electron microscopy with the results of energy-dispersive X-ray spectroscopy and X-ray diffraction, it is confirmed that the particles observed at or near the grain centres of refined Al alloys are pro-peritectic Al3Nb particles. The crystallographic matching between the Al3Nb particles and Al grains has also been evaluated using an edge-to-edge matching model and further verified using electron backscatter diffraction and transmission electron microscopy. It is found that there are reproducible crystallographic orientation relationships between the Al3Nb particles and Al grains, and the experimental results are consistent with the predictions of the edge-to-edge matching model. This implies that the pro-peritectic Al3Nb particles are favourable nucleation sites for Al grains from the crystallographic point of view. Furthermore, the analysis of the size distribution of Al3Nb particles reveals that the Al3Nb particles at the grain centres have relatively large particle size, which also corroborates the high potency of Al3Nb according to the free growth model. It is therefore concluded that the significant grain refinement resulting from the addition of Nb is predominantly attributed to thein situformed Al3Nb particles which promote grain refinementviaenhanced heterogeneous nucleation.

scholarly journals Effect of grain refinement on the microstructure, dendrite coherency and porosity of AZ91E magnesium alloy

2021 ◽  
Author(s):  
Mihai Vlasceanu
Keyword(s):  
Magnesium Alloy ◽  
Grain Refinement ◽  
Growth Mechanism ◽  
Solid Fraction ◽  
Dendrite Growth ◽  
Dendritic Morphology ◽  
Al Alloys ◽  
Mg Alloys ◽  
Grain Refiner ◽  
Dendrite Coherency

Magnesium (Mg) alloys present a promising alternative to aluminum (Al) alloys in lightweight applications. However, relative to Al alloys, Mg alloys have poor castability. Castability is influenced significantly by the dendrite coherency point (DCP), which represents the temperature, time, and solid fraction at which an interlocking solid network forms during solidification. An increase in the solid fraction at coherency may improve the castability of the alloy and reduce casting defects such as porosity, hot tears and misruns. A successful method for increasing the solid fraction at the DCP in Al alloys involves the use of grain refiners such as titanium (Ti). However, the influence of Ti refiners on the DCP in Mg alloys has not been thoroughly investigated. The objective of this research was to study the effect of Al-5Ti-1B refiner on the dendrite growth mechanism, DCP and porosity of AZ91E magnesium alloy. This thesis is a pioneering effort in relating the grain refinement effect of Ti on the DCP, coherency solid fraction, and porosity development during the solidification of Mg alloy, AZ91E. It represents an important step in improving the castability of Mg alloys. Varying levels of Al-5Ti1B grain refiner (0.005, 0.05, 0.1, 0.2, and 0.3 wt.% Ti) were added to AZ91E. The effect of Al-5Ti-1B grain refiner on the microstructure and dendrite growth mechanism of AZ91E was investigated. Quench experiments were performed to observe transformations in the dendritic morphology that resulted from the refiner additions. The growth rate and DCP were determined using the rheological method. The changes in porosity levels were determined for the grain refiner additions.

Grain Refinement Mechanism and Effective Nucleation Phase of Al-5Ti-1B Master Alloy

2017 ◽  
Vol 898 ◽  
pp. 1231-1235 ◽  
Author(s):  
Shun Cheng Wang ◽  
Ji Lin Li ◽  
Chun Lei Gan ◽  
Kai Hong Zheng
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Master Alloy ◽  
Pure Aluminum ◽  
Grain Refiner ◽  
Crystal Nucleus ◽  
Master Alloys ◽  
Refinement Mechanism ◽  
Nucleation Phase ◽  
Heterogeneous Nucleus

The Al-5Ti-1B, Al-10Ti, Al-4B master alloys and TiB2 powder were applied to refine the pure aluminum, respectively. The effects of the TiAl3 phase, TiB2 particle, and AlB2 phase on the grain size of pure aluminum were compared. The grain refinement mechanism of the Al-5Ti-1B grain refiner was studied. The results showed that the TiAl3 phase was an effective heterogeneous nucleus of the α-Al grain. But the TiAl3 phase in the Al-5Ti-1B grain refiner was not the heterogeneous nucleus of the α-Al grain due to its re-melting in the Al melt. The separate TiB2 particle or AlB2 phase was not the heterogeneous nucleus of the α-Al grain. However, the TiB2 coated by the TiAl3 phase can be the effective heterogeneous nucleus of the α-Al grain. The grain refinement mechanism of the Al-5Ti-1B grain refiner can be summarized as follows: when the Al-5Ti-1B grain refiner is added into the Al melt, the TiAl3 phases are re-melted to release the Ti atoms, while the TiB2 particles are remaining in the Al melt. During the solidification of the Al melt, the Ti atoms are segregating on the surface of TiB2 particles to form the TiAl3 phases. The TiB2 particles coated by the TiAl3 phases then reacts with the Al melt to generate α-Al crystal nucleus.

Influence of SiC Particles on the Grain Refinement of an Mg-Al Alloy

2009 ◽  
Vol 618-619 ◽  
pp. 445-448 ◽  
Author(s):  
Andreas Schiffl ◽  
Mark Easton
Keyword(s):  
Grain Size ◽  
Phase Equilibria ◽  
Grain Refinement ◽  
Al Alloys ◽  
Al Alloy ◽  
Grain Refiner ◽  
Sic Particles ◽  
Ternary Carbides

SiC particles are effective grain refiners in Mg-Al alloys. Several investigations, from different researchers, into their effect on a range of alloys with different Al contents has been undertaken and it has been found that the greatest reduction in grain size occurs in alloys having low Al contents. Performing grain refinement studies on a range of alloy contents also allows for further investigation into the mechanisms of grain refinement. It was found that the size of the SiC particles is also important in magnesium grain refinement. However, the presence of Mg2Si in the microstructure and the consideration of phase equilibria suggest that SiC can transform into other binary or ternary carbides. If such carbides are formed, they may also act as an effective grain refiner for Mg-Al alloys. In this study, the possibility of formation of new carbides (Al4C3, Al2MgC2, Mn7C3, Mg2C, Mg2C3, Al2CO etc.) and their ability to be good grain refiners for Mg-Al alloys is discussed.

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