scholarly journals Review, Role of L12 Modified (Al1−xMex)3Ti Intermetallic Compounds on Heterogeneous Nucleation of Alpha Aluminum Grains

2020 ◽  
Vol 326 ◽  
pp. 06008
Author(s):  
Yoshimi Watanabe
Keyword(s):  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Heterogeneous Nucleation ◽  
Nucleation Site ◽  
High Symmetry ◽  
Cast Aluminum ◽  
Heterogeneous Nucleation Site ◽  
Lattice Constants ◽  
Refining Performance

Al3Ti intermetallic compound with the tetragonal D022 structure undergoes a phase transformation to the high-symmetry L12 cubic structure by addition of third elements, Me. The lattice constants of some L12 modified (Al1−xMex)3Ti intermetallic compounds are closed to that of alpha aluminum. Therefore, it is expected that the addition of L12 modified (Al1−xMex)3Ti intermetallic compound particles show good grain refining performance of cast aluminum. In this paper, our recent results on novel refines containing heterogeneous nucleation site particles of L12 modified (Al1−xMex)3Ti intermetallic compounds have been reviewed.

Effect of Manganese Sulphide Size on the Precipitation of Tin Heterogeneous Nucleation in as-Cast Steel

2015 ◽  
Vol 34 (3) ◽  
Author(s):  
Guilin Sun ◽  
Bo Song ◽  
Sufen Tao ◽  
Zeyun Cai
Keyword(s):  
Contact Angle ◽  
Theoretical Model ◽  
Grain Boundaries ◽  
Heterogeneous Nucleation ◽  
Cast Steel ◽  
Nucleation Site ◽  
High Concentration ◽  
Heterogeneous Nucleation Site

AbstractTramp elements in steels such as tin have been thought harmful because of the hot brittleness at grain boundaries and will be enriched in new steels because of difficulty of removal. It has been an important and difficult matter for metallurgist to use these elements. In the present paper, the as-cast steel containing high concentration of tin is prepared in laboratory and tin precipitates at the manganese sulphide inclusions have been found. A theoretical model is established to calculate the size of manganese sulphide inclusions acted as the heterogeneous nucleation site of tin precipitation. The results show that the inclusions with the smaller contact angle between tin precipitate is more advantageous to be the nucleus of tin heterogeneous nucleation. In this experiment, the manganese sulphide inclusions whose size is 2~4 μm in diameter can act as the nuclei of the nucleation of tin precipitation.

scholarly journals Microstructural Stability of Ti based Composites Fabricated by Spark Plasma Sintering

2020 ◽  
Vol 321 ◽  
pp. 03023
Author(s):  
Yoshimi Watanabe ◽  
Miwa Hattori ◽  
Tadachika Chiba ◽  
Hisashi Sato
Keyword(s):  
Spark Plasma Sintering ◽  
Heterogeneous Nucleation ◽  
Elevated Temperatures ◽  
Nucleation Site ◽  
Layer By Layer ◽  
Microstructural Stability ◽  
Heterogeneous Nucleation Site ◽  
Pinning Effect ◽  
Plasma Sintering ◽  
Spark Plasma

In our previous study, the effects of TiC heterogeneous nucleation site particles on formability and microstructure of additive manufactured (AMed) Ti-6Al-4V products were studied. It was found that the addition of TiC particles decreased the grain size of primary β phase in AMed Ti-6Al-4V samples, since TiC particles act as heterogeneous nucleation sites. It is also found that the density of AMed Ti-6Al-4V samples could be increased by addition of TiC particles. It is expected that solid-state β-grain growth by the high temperature thermal cycles associated with layer-by-layer manufacturing can be suppressed by the pinning effect of TiC heterogeneous nucleation site particles. In this study, the pinning effect of heterogeneous nucleation site particles on microstructure of Ti at elevated temperatures is studied. For this purpose, Ti-0.3vol%TiC samples fabricated by spark plasma sintering (SPS) are used as the model materials, and microstructure and hardness of the samples heat treated at elevated temperatures are studied.

Mechanism on Heterogeneous Nucleation of the Primary Al Phase on TiAl3 of a Hot-Dip Zn-11%Al-3%Mg-0.2%Si Coating on Steel Sheet

2010 ◽  
Vol 638-642 ◽  
pp. 2787-2792 ◽  
Author(s):  
Kazuhiko Honda ◽  
Kohsaku Ushioda ◽  
Wataru Yamada
Keyword(s):  
Heterogeneous Nucleation ◽  
Steel Sheet ◽  
Steel Substrate ◽  
Ternary Eutectic ◽  
Dip Coating ◽  
Nucleation Site ◽  
Fiber Texture ◽  
Solidification Structure ◽  
Heterogeneous Nucleation Site ◽  
Perfect Lattice

The solidification structure of a hot-dip Zn-11%Al-3%Mg-0.2%Si coating with a Ti addition on a steel substrate was investigated. Steel sheet was coated using a laboratory hot-dip galvanizing simulator. The coating was subsequently characterized via optical and high resolution scanning electron microscopy with EBSD and high temperature X-ray diffractometry. The hot-dip coating consisted of a combination of a Zn/Al/MgZn2 ternary eutectic structure, primary Al phase and MgZn2 phase. TiAl3 acts as a heterogeneous nucleation site for Al, which was shown to have perfect lattice coherency with TiAl3 as epitaxial Al growth from the TiAl3 was found. The growth direction of Al is along <110> and has a random texture, whereas Zn has a rather strong ND//<0001> fiber texture.

Grain Refinement of Cast Aluminum by Heterogeneous Nucleation Sites

2019 ◽  
Author(s):  
Yoshimi Watanabe ◽  
Hisashi Sato
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Vital Role ◽  
Grain Refining ◽  
Cast Aluminum ◽  
Friction Stir ◽  
Fragmentation Behavior ◽  
Nucleation Sites ◽  
Refining Performance ◽  
Cold Rolled

Grain refinement plays a vital role in cast and wrought Al alloys. To achieve a grain refined cast microstructure, addition of Al-Ti, Al-Ti-B, and Al-Ti-C refiners has become a common industrial practice. The refiners introduce a large number of particles such as Al3Ti, TiB2, or TiC into the Al melt, and these particles act as heterogeneous nucleation sites for α-Al grains. In this article, some of the main theories of grain refining by refiners, and the crystal structure and shape of Al3Ti in Al-Ti refiner are briefly summarized to outline the physical aspects of grain refinement. Then, our results on grain refining performance of pure Al casts by equal-channel angular-pressed Al-11vol%Al3Ti refiner, cold-rolled Al-11vol%Al3Ti refiner, Al-10vol%Ti refiner, and Al-10vol% L12-type Al2.7Fe0.3Ti refiner will be described. Fragmentation behavior of Al3Ti platelets in Al-Ti refiner by friction stir processing is also presented.

scholarly journals Heat Treatment-Induced Microstructure and Property Evolution of Mg/Al Intermetallic Compound Coatings Prepared by Al Electrodeposition on Mg Alloy from Molten Salt Electrolytes

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1407
Author(s):  
Tianyu Yao ◽  
Kui Wang ◽  
Haiyan Yang ◽  
Haiyan Jiang ◽  
Jie Wei ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Intermetallic Compound ◽  
Intermetallic Compounds ◽  
Mg Alloy ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
Alloy Matrix ◽  
Comprehensive Properties ◽  
Compound Coatings ◽  
Compound Coating

A method of forming an Mg/Al intermetallic compound coating enriched with Mg17Al12 and Mg2Al3 was developed by heat treatment of electrodeposition Al coatings on Mg alloy at 350 °C. The composition of the Mg/Al intermetallic compounds could be tuned by changing the thickness of the Zn immersion layer. The morphology and composition of the Mg/Al intermetallic compound coatings were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and electron backscattered diffraction (EBSD). Nanomechanical properties were investigated via nano-hardness (nHV) and the elastic modulus (EIT), and the corrosion behavior was studied through hydrogen evolution and potentiodynamic (PD) polarization. The compact and uniform Al coating was electrodeposited on the Zn-immersed AZ91D substrate. After heat treatment, Mg2Al3 and Mg17Al12 phases formed, and as the thickness of the Zn layer increased from 0.2 to 1.8 μm, the ratio of Mg2Al3 and Mg17Al12 varied from 1:1 to 4:1. The nano-hardness increased to 2.4 ± 0.5 GPa and further improved to 3.5 ± 0.1 GPa. The Mg/Al intermetallic compound coating exhibited excellent corrosion resistance and had a prominent effect on the protection of the Mg alloy matrix. The control over the ratio of intermetallic compounds by varying the thickness of the Zn immersion layer can be an effective approach to achieve the optimal comprehensive performance. As the Zn immersion time was 4 min, the obtained intermetallic compounds had relatively excellent comprehensive properties.

The Formation Mechanism of Equiaxed Crystals in Pure Aluminum Solidification Structure under the Al-Ti-C Master Alloy

2013 ◽  
Vol 668 ◽  
pp. 865-869
Author(s):  
Wan Wu Ding ◽  
Wen Jun Zhao ◽  
Tian Dong Xia
Keyword(s):  
Transition Zone ◽  
Formation Mechanism ◽  
Master Alloy ◽  
Heterogeneous Nucleation ◽  
Pure Aluminum ◽  
Solidification Structure ◽  
Impact Mechanism ◽  
Tic Particle ◽  
The Impact

The influence of different solidified velocities on the structure of pure aluminum during the process of refinement by Al-5Ti-0.6C master alloy was studied and the impact mechanism was discussed. The results show that at the same solidified velocity, with the increase of the amount of Al-5Ti-0.6C master alloy, in the solidified structure of pure aluminum, columnar crystals will gradually decrease, while equiaxed crystals will gradually increase. But in the case when the level of addition is the same, the faster the solidified velocity, the greater the number of equiaxed crystals will be in the ingot microstructure. The formation of equiaxed crystals is the result of the dual role of dissociation of crystal particles and heterogeneous nucleation of “TiC particle---Ti transition zone”.

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