scholarly journals Relationship between TiB2 agglomerate size and grain refinement effectiveness of Al-Ti-B grain refiner

2021 ◽  
Vol 71 (9) ◽  
pp. 409-414
Author(s):  
Akihiro Minagawa ◽  
Shogo Furuta ◽  
Naoki Omura ◽  
Yuichiro Murakami ◽  
Masanori Tsunekawa
Keyword(s):  
Grain Refinement ◽  
Grain Refiner ◽  
Agglomerate Size

scholarly journals The Interactions Between Oxide Film Inclusions and Inoculation Particles TiB2 in Aluminum Melt

2021 ◽  
Author(s):  
Jiawei Yang ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Yanjun Li
Keyword(s):  
Grain Refinement ◽  
Master Alloy ◽  
Large Fraction ◽  
Oxide Films ◽  
Grain Refiner ◽  
Particle Sedimentation ◽  
Aluminum Melt ◽  
Refinement Efficiency ◽  
Long Time ◽  
Commercial Purity Aluminum

AbstractIn this work, a systematic study on the interactions between aluminum oxide films and TiB2 grain refiner particles and their effect on grain refinement behavior have been conducted. Oxide films were introduced into a commercial purity aluminum melt by adding AA 6061 alloy chips while the grain refiner particles were introduced by adding Al-3T-1B master alloy. Strong sedimentation of TiB2 grain refiner particles was observed in aluminum melt without chip addition during long-time settling. Most of the TiB2 particles were settled and accumulated at the bottom of crucible. In contrast, the sedimentation of TiB2 particles is much less in the melt with the addition of oxide films. A large fraction of TiB2 particles were found to be adhered to the oxide films located at the top part of the crucible, which inhibited the sedimentation of grain refiner particles. TP-1 type tests were also done to study the grain refinement efficiency of Al-3Ti-1B master alloy under different melt cleanliness and settling time. It is found that sedimentation of TiB2 particles greatly reduces the grain refinement efficiency. The introduction of oxide films seems to slightly alleviate the fading effect. This is owing to the strong adherence between the oxide films and TiB2 particles, which leads to a retardation of particle sedimentation.

Effect of Solute Ta on Grain Refinement of Al-7Si-0.3Mg Based Alloys

2022 ◽  
Vol 327 ◽  
pp. 54-64
Author(s):  
Ivo Spacil ◽  
David Holec ◽  
Peter Schumacher ◽  
Jiehua Li
Keyword(s):  
Grain Refinement ◽  
Density Functional ◽  
Dft Calculation ◽  
Interface Energy ◽  
Special Focus ◽  
Grain Refiner ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Sandwich Configuration ◽  
Scanning Electron

Different Ta concentrations together with stochiometric grain refiner (Al-2.2Ti-1B) in Al-Si-Mg based alloys were investigated with the aim to elucidate grain refinement mechanisms. Post-solidification microstructure was characterised using optical microscopy and scanning electron microscopy (SEM), with a special focus on the Ta-rich layer (more likely to be Al3Ta) on the basal planes (0001) of TiB2. A significant grain refinement was observed by using the solute Ta together with stochiometric grain refiner (Al-2.2Ti-1B). In order to further elucidate the formation of Ta-rich layer on the basal planes (0001) of TiB2, the Density Functional Theory (DFT) calculation were also performed to determine the interface energies of different interfaces and sandwich configurations, including Al (111), Al3Ti (112) and Al3Ta (112) at the interface of TiB2 basal plane (0001). It was found that the interface energy for Ti-terminated TiB2 at the interface throughout all configurations involved in this paper is lower than that for B-terminated TiB2, indicating that Ti-terminated TiB2 is more favourable. It was also found that the Al3Ta configuration yields the same interface energies as the Al3Ti configuration. Furthermore, the interface energy of the sandwich configuration also shows nearly identical values along the TiB2 // Al3Ti and TiB2 // Al3Ta interface energy, strongly indicating that the solute Ti can be fully replaced by the solute Ta.

Grain Refinement and Hot Tearing of Aluminium Alloys - How to Optimise and Minimise

2009 ◽  
Vol 630 ◽  
pp. 213-221 ◽  
Author(s):  
Mark Easton ◽  
David H. StJohn ◽  
Lisa Sweet
Keyword(s):  
Grain Refinement ◽  
Aluminium Alloys ◽  
Hot Tearing ◽  
Key Factors ◽  
Grain Refiner ◽  
Factors Affecting ◽  
Equiaxed Grains

Grain refinement and hot tearing are important key factors affecting the quality of castings. There have been substantial advances in the understanding of both of these phenomena over the last two decades. The paper discusses strategies for obtaining the lowest cost grain refiner addition and provides an explanation for how the refinement of equiaxed grains leads to a reduction in hot tear susceptibility. However, it also provides a warning that adding more grain refiner may not be better for reducing hot tear susceptibility. Alloy factors affecting hot tearing are also discussed. Finally, a list of six key considerations is provided to help casthouse and foundry engineers when trying to optimise grain refinement and reduce hot tearing.

scholarly journals Novel grain refinement of AZ91E magnesium alloy and the effect on hot tearing during solidfication

2021 ◽  
Author(s):  
Abdallah Elsayed
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Hot Tearing ◽  
Grain Refining ◽  
Grain Refiner ◽  
Structural Applications ◽  
Hot Tearing Susceptibility

For the A1-5Ti-1B grain refiner, the addition of 0.1 wt.% provided a 68 % reduction in grain size as compared to the unrefined AZ91E alloy at a holding time of five minutes. Grain growth restriction by TiB₂ particles was the source of grain refinement. With the addition of A1-5Ti-1B, only a small reduction in hot tearing susceptibility ws observed because large TiA1₃ particles bonded poorly with the eutectic and blocked feeding channels.The addition of 1.0 wt.% A1-1Ti-3B provided a grain size reduction of 63% as compared to the unrefined AZ91E alloy at a holding time of five minutes. The grain refinement with A1-1Ti-3B addition was attributed to a combination of TiB₂ grain growth restriction and A1B₂ nucleating sites. A significant reduction in hot tearing susceptibility was observed with A1-1Ti-3B addition as a result of a higher cooling rate and shorter local soldification time as compared to the AZ91E alloy. The reduction in hot tearing susceptibility was attributed to the good interface between eutectic and TiB₂ particles. Both grain refiners demonstrated a good resistance to fading during the holding times investigated. In addition, the AZ91E + A1-5Ti-1B and AZ91E + A1-1Ti-3B castings showed much fewer dislocation networks as compared to the untreated AZ91E casting.The development of efficient A1-Ti-B refiners can also improve castability of magnesium alloys. In addition, the fade resistant A1-Ti-B grain refiners can reduce operating costs and maintain productivity on the foundry floor. Thus, magnesium alloy with A1-Ti-B treatment have the potential for more demanding structural applications in the automobile and aerospace industries. Vehicle weight in the aerospace and automotive industries directly impacts carbon emissions and fuel efficiency. An increase in the use of lightweight materials for structural applications will result in lighter vehicles. Low density materials, such as magnesium (1.74 g/cm³) are a potential alternative to aluminium (2.70 g/cm³), to reduce component weight in structural applications.However, current magnesium alloys still do not have adequate mechanical properties and castability to meet the performance specifications of the automotive and aerospace industries. Grain refinement can significantly improve mechanical properties and reduce hot tearing during permanent mould casting. Recently, Al-Ti-B based grain refiners have shown potential in grain refining magnesium-aluminum alloys such as AZ91E. This study investigates the grain refining efficiency and fading of A1-5Ti-1B and A1-1Ti-3B in AZ91E magnesium alloy and their subsequent effect on hot tearing.The grain refiners were added at 0.1, 0.2, 0.5 and 1.0 wt.% levels. For the grain refinement and fading experiments, the castings were prepared using graphite moulds with holding times of 5, 10 and 20 minutes. For the hot tearing experiments, castings were produced representing the optimal addition level of each grain refiner. The castings were prepared using a permanent mould with pouring and mould temperatures of 720 and 180 ºC, respectively. The castings were characterized using SEM, TEM, optical microscopy and thermal analysis.

Abnormal Grain Refinement Behavior in High-Pressure Die Casting of Pure Mg with Addition of Zr as Grain Refiner

JOM ◽  
2018 ◽  
Vol 70 (11) ◽  
pp. 2555-2560 ◽  
Author(s):  
Wenchao Yang ◽  
Shouxun Ji ◽  
Ruirong Zhang ◽  
Jun Zhang ◽  
Lin Liu
Keyword(s):  
High Pressure ◽  
Grain Refinement ◽  
Die Casting ◽  
Grain Refiner ◽  
High Pressure Die Casting ◽  
Pressure Die Casting

Microstructure of Heat-Treated Al-Al2.7Fe0.3Ti Grain Refiner and Its Grain Refinement Ability

2016 ◽  
Vol 2016 (0) ◽  
pp. G0400505
Author(s):  
Motoko YAMADA ◽  
Takayuki HAMADA ◽  
Yoshimi WATANABE ◽  
Hisashi SATO
Keyword(s):  
Grain Refinement ◽  
Grain Refiner ◽  
Heat Treated

Grain Refinement Performance of Al Cast Using Machining Chips

2010 ◽  
Vol 654-656 ◽  
pp. 1444-1447 ◽  
Author(s):  
Yoshimi Watanabe ◽  
Kenichi Tabushi ◽  
Hisashi Sato ◽  
Eri Miura-Fujiwara
Keyword(s):  
Cooling Rate ◽  
Grain Refinement ◽  
Nucleation Site ◽  
Grain Refiner ◽  
Metallic Mold ◽  
Refinement Effect

In this study, grain refinement performance of as-cast Al using machining chip of Al instead of the grain refiner is investigated. At first, the machining chips of pure Al are placed in metallic mold. Then, pure Al melt is inserted into the mold with the machining chips. From the microstructure of the as-cast Al using the machining chips, it is found that this machining chip in mold can induce grain refinement of as-cast Al. The increment of the Al chips enhances the grain refinement of the as-cast Al. Moreover, it is shown that preheating the mold can reduce the pore inside as-cast Al using the machining chips. This grain-refinement effect by the machining chips would come from the enhancement of cooling rate and the role of the nucleation site. Therefore, it is concluded that the machining chips of Al can enhance the grain refinement of as-cast Al.

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.

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