Grain Refinement of Al Cast by Novel Al-Al2.5Cu0.5Ti Refiner Fabricated by Cold Pressing

2014 ◽  
Vol 783-786 ◽  
pp. 276-281
Author(s):  
Kunika Yamanaka ◽  
Hisashi Sato ◽  
Yoshimi Watanabe
Keyword(s):  
Intermetallic Compound ◽  
Grain Refinement ◽  
Lattice Constant ◽  
Heterogeneous Nucleation ◽  
Type Structure ◽  
The Novel ◽  
Cold Pressing ◽  
Nucleation Sites ◽  
Cubic Structure

It is reported that alloying with Cu causes the transformation from the D022 type structure of Al3Ti into L12 cubic structure. Since the lattice constant of Al2.5Cu0.5Ti with L12 structure is a = 0.3927 nm, smaller disregistry value between Al and Al2.5Cu0.5Ti can be achieved. In this study, novel refiner for Al cast containing Al2.5Cu0.5Ti intermetallic compound particles with L12 structure is fabricated by cold pressing. It is found that the grains of Al cast are partially refined by using the novel refiner, although microstructure of Al grain is not homogeneous. In this way, the Al2.5Cu0.5Ti intermetallic compound particles with L12 structure can become favorable heterogeneous nucleation sites for Al cast.

Master Alloys for Grain Refinement

2019 ◽  
Author(s):  
Xiaoming Wang
Keyword(s):  
Grain Refinement ◽  
Heterogeneous Nucleation ◽  
Aluminum Matrix ◽  
Industrial Applications ◽  
Hard Particles ◽  
Nucleation Sites ◽  
Major Disadvantage ◽  
Master Alloys ◽  
Volume Production ◽  
Low Volume

Master alloys are routinely added into aluminum melts before casting for grain refinement purposes. The widely used master alloys contain titanium and boron in the forms of Al3Ti and TiB2 particles in an aluminum matrix. Upon addition into aluminum melts, Al3Ti dissolves into the aluminum melts and promotes the heterogeneous nucleation of the α-Al grains while restricting the growth of α-Al grains through a constitutional cooling effect in solidification. Meanwhile, TiB2 is stable and acts as a substrate for the heterogeneous nucleation of α-Al grains through a layer of Al3Ti on the surface. Sharing these in common, different mechanisms for the grain refinement of aluminum by Al-Ti-B-type master alloys have been proposed. Another kind of popular master alloys is Al-Ti-C, which is used in a lesser extent for the grain refinement of Al alloys containing elements that are poisoning Al-Ti-B master alloys. Titanium and carbon exist as Al3Ti and TiC particles. TiC is not as stable as TiB2 and decomposes in aluminum melts. TiC in Al-Ti-C therefore acts as heterogeneous nucleation sites for α-Al grains similar to TiB2. However, the fading of Al-Ti-C master alloys is irreversible, which is the major disadvantage of Al-Ti-C master alloys. Al-Ti master alloys do not contain hard particles and are used industrially for products that are sensitive to hard TiB2 and TiC particles. There are also other master alloys that show high grain refinement potentials in lab tests but have never been used industrially for mainly low-volume production and high costs. This article gives an overview of the grain refinement of aluminum by master alloys with an emphasis on Al-Ti-B master alloys, from the production to the industrial applications of the master alloys.

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.

Mössbauer studies and magnetic properties of the novel ternary europium pnictides LiEuPn (Pn=P, As, Sb, Bi) with TiNiSi type structure

2002 ◽  
Vol 4 (5) ◽  
pp. 695-700 ◽  
Author(s):  
M. Prill ◽  
B.D. Mosel ◽  
W. Müller-Warmuth ◽  
J. Albering ◽  
Th. Ebel ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Type Structure ◽  
The Novel ◽  
Mössbauer Studies

scholarly journals Roles of Lanthanum and Cerium in Grain Refinement of Steels during Solidification

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 884 ◽  
Author(s):  
Yunping Ji ◽  
Ming-Xing Zhang ◽  
Huiping Ren
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Rare Earths ◽  
Heterogeneous Nucleation ◽  
The Past ◽  
Cast Steels ◽  
Steel Castings ◽  
Similarity And Difference

Refinement of as-cast structures is one of the most effective approaches to improve mechanical properties, formability, and surface quality of steel castings and ingots. In the past few decades, addition of rare earths (REs), lanthanum and cerium in particular, has been considered as a practical and effective method to refine the as-cast steels. However, previous reports contained inconsistent, sometime even contradictory, results. This review summaries the major published results on investigation of the roles of lanthanum or/and cerium in various steels, provides reviews on the similarity and difference of previous studies, and clarifies the inconsistent results. The proposed mechanisms of grain refinement by the addition of lanthanum or/and cerium are also reviewed. It is concluded that the grain refinement of steels by RE additions is attributed to either heterogeneous nucleation on the in-situ formed RE inclusions, a solute effect, or the combined effect of both. The models/theories for evaluation of heterogeneous nucleation potency and for solute effect on grain refinement of cast metals are also briefly summarized.

Geometric Design of Heterogeneous Nucleation Sites on Biocompatible Surfaces

2013 ◽  
Vol 13 (8) ◽  
pp. 3835-3841 ◽  
Author(s):  
Vilmalí López-Mejías ◽  
Allan S. Myerson ◽  
Bernhardt L. Trout
Keyword(s):  
Heterogeneous Nucleation ◽  
Geometric Design ◽  
Nucleation Sites

Influence of Ni particle addition on grain refinement of Cu-Sn intermetallic compound joints bonded at various temperatures

2019 ◽  
Vol 774 ◽  
pp. 721-726 ◽  
Author(s):  
X.J. Guo ◽  
Z.L. Li ◽  
X.G. Song ◽  
H. Tian ◽  
H.J. Dong ◽  
...  
Keyword(s):  
Intermetallic Compound ◽  
Grain Refinement ◽  
Particle Addition

Heterogeneous Formation of Oriented Silicon Oxynitride on α-Si3N4 Seed Crystals : Habits And Radiation Stability

1999 ◽  
Vol 5 (S2) ◽  
pp. 778-779
Author(s):  
R.W Carpenter ◽  
W Braue ◽  
M.J. Kim
Keyword(s):  
Silicon Nitride ◽  
Heterogeneous Nucleation ◽  
Radiation Stability ◽  
Silicon Oxynitride ◽  
Minor Constituent ◽  
Sintering Aids ◽  
Sintering Aid ◽  
Nucleation Sites ◽  
Heterogeneous Formation ◽  
A Minor

Lath-like silicon oxynitride crystals have often been observed in the microstructure of silicon nitride based ceramics after processing. They are usually located in glassy regions which are siliceous solidified sintering aid liquid, and usually contain a small (∼100nm) a-Si3N4 crystal. These nitride crystals are considered to be seeds, incompletely dissolved in the melt, that are heterogeneous nucleation sites for the oxynitride crystals. We present here the first observations of morphological and crystallographic habits between the seed nanocrystals and the host oxynitride laths.Fig. 1 shows a typical oxynitride lath containing a nitride seed crystal. The lath is surrounded by glass and ß-Si3N4 particles, and a small cristobalite particle (a minor constituent). This microstructure is from an Si02-Si3N4 ceramic processed with Al2O3 sintering aid. The same oxynitride lath/seed structures were observed when other sintering aids (eg. Y2O3, MgO, ZrO2) were used, so they are independent of sintering aid.

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