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.

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.

scholarly journals Effects of modifying the hypoeutectic AlMg5Si2Mn alloy via addition of Al10Sr and/or Al5TiB

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
P. Snopiński ◽  
M. Król ◽  
T. Wróbel ◽  
K. Matus ◽  
A. Woźniak ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Grain Refinement ◽  
Spectroscopic Characterization ◽  
Nucleation Temperature ◽  
Alloy Sample ◽  
Nucleation Sites ◽  
Master Alloys ◽  
Ti Particles ◽  
Prepared Alloy ◽  
Refinement Effect

AbstractThis work demonstrates that the combined addition of Al10Sr and Al5TiB master alloys to the AlMg5Si2Mn effectively refines the grain microstructure and partially modifies the eutectic Mg2Si phase. Thorough spectroscopic characterization reveals that the grain refinement effect is due to Al3Ti particles acting as nucleation sites for α-Al grains, and the increased nucleation temperature of α-Al is due to Al10Sr addition. It is also determined that TiB2 particles can act as nucleation substrates for the primary Mg2Si phase. The prepared alloy sample with the finest microstructure (treated with both Al10Sr and Al5TiB) exhibits the greatest corrosion resistance among all tested samples.

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.

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.

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.

The influence of gadolinium on Al–Ti–C master alloy and its refining effect on AZ31 magnesium alloy

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenxue Fan ◽  
Hai Hao
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Master Alloy ◽  
Cast Alloy ◽  
Az31 Magnesium Alloy ◽  
Synthesis Mechanism ◽  
Refining Effect ◽  
Master Alloys

Abstract Grain refinement has a significant influence on the improvement of mechanical properties of magnesium alloys. In this study, a series of Al–Ti–C-xGd (x = 0, 1, 2, 3) master alloys as grain refiners were prepared by self-propagating high-temperature synthesis. The synthesis mechanism of the Al–Ti–C-xGd master alloy was analyzed. The effects of Al–Ti–C-xGd master alloys on the grain refinement and mechanical properties of AZ31 (Mg-3Al-1Zn-0.4Mn) magnesium alloys were investigated. The results show that the microstructure of the Al–Ti–C-xGd alloy contains α-Al, TiAl3, TiC and the core–shell structure TiAl3/Ti2Al20Gd. The refining effect of the prepared Al–Ti–C–Gd master alloy is obviously better than that of Al–Ti–C master alloy. The grain size of AZ31 magnesium alloy was reduced from 323 μm to 72 μm when adding 1 wt.% Al–Ti–C-2Gd master alloy. In the same condition, the ultimate tensile strength and elongation of as-cast alloy were increased from 130 MPa, 7.9% to 207 MPa, 16.6% respectively.

Neue Fertigungssteuerung in der Ingenieurkeramik*/New approach to manufacturing control in engineering ceramics

2015 ◽  
Vol 105 (03) ◽  
pp. 109-114
Author(s):  
U. Bracht ◽  
F. Arzberger ◽  
F. Schulenburg
Keyword(s):  
Lean Manufacturing ◽  
Lean Production ◽  
Control Unit ◽  
Manufacturing Processes ◽  
Small Companies ◽  
Complex Environment ◽  
New Approach ◽  
Manufacturing Control ◽  
Volume Production ◽  
Low Volume

Auch kleinere Unternehmen mit komplexen Herstellungsprozessen müssen heute in der Kleinserie die Effizienz und Geschwindigkeit in der Produktion erhöhen. Zentraler Bestandteil ist dabei eine schlanke Fertigungssteuerung in einem ganzheitlichen Produktionssystem. Der Fachbeitrag zeigt, wie auch bei hoher Komplexität wesentliche Ansätze der „Lean Production“ genutzt werden, um die Produktion von Ingenieurkeramiken durch die intelligente Vernetzung bereichsspezifischer Methoden zu optimieren.   Today, even small companies with complex manufacturing processes in low-volume production have to improve efficiency and speed in manufacturing. A core aspect is lean manufacturing control within an overall production system. This article shows how the main approaches of Lean Production can be applied even to a highly complex environment. The intelligent integration of specific methods for each control unit helps to enhance the production of ceramics.

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