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.

scholarly journals Effect of Inclusion and Filtration on Grain Refinement Efficiency of Aluminum Alloy

2022 ◽  
Author(s):  
Jiawei Yang ◽  
Yijiang Xu ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Ulf Tundal ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Oxide Films ◽  
Pilot Scale ◽  
Ceramic Foam ◽  
Grain Refiner ◽  
Aluminum Melt ◽  
Refinement Efficiency ◽  
Master Alloys ◽  
And Performance

AbstractIt is well known that the filtration efficiency of ceramic foam filters (CFF) on aluminum melt can be significantly reduced by the addition of grain refiner particles under a high inclusion load. Also, it is usually considered that the filtration process has little impact on grain refinement efficiency. In this work, the influence of inclusions and filtration on the grain refinement effect of AA 6060 alloy has been studied. This was done through TP-1 type solidification experiments where the aluminum melt prior to and after the filter during a pilot-scale filtration test was investigated. In the experiments, 80 PPi CFFs were used to filtrate aluminum melt with an ultra-high inclusion load and two addition levels of Al–3Ti–1B master alloys. It is found that both inclusions and filtration significantly reduce the grain refinement efficiency of the grain refiner master alloys. A detailed characterization of the used filters shows that the reduction of grain refinement efficiency is due to the strong adherence of TiB2 particles to the oxide films, which are blocked by the CFF during filtration. A grain size prediction model based on deterministic nucleation mechanisms and dendritic growth kinetics has been applied to calculate the solidification grain size and estimate the loss of effective grain refiner particles during filtration. It is shown that due to the strong adherence between TiB2 particles and oxide films in the melt, the high addition level of aluminum chips also has an influence on reducing the grain refinement efficiency of aluminum melt without filtration. The results of this study extended our understanding of the behavior and performance of inoculant particles in CFF and their interactions with the inclusions.

scholarly journals The Influences of Grain Refiner, Inclusion Level, and Filter Grade on the Filtration Performance of Aluminum Melt

2021 ◽  
Author(s):  
Jiawei Yang ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Ulf Tundal ◽  
Stig Tjøtta ◽  
...  
Keyword(s):  
Oxide Films ◽  
Pilot Scale ◽  
Ceramic Foam ◽  
Grain Refiner ◽  
Filtration Process ◽  
Aluminum Melt ◽  
Filtration Performance ◽  
Master Alloys ◽  
Inclusion Level ◽  
High Level

AbstractThe addition of grain refiner particles in the aluminum melt is known to reduce the filtration efficiency of ceramic foam filter (CFF). In the present work, a systematic study on the influence of the addition level of Al-Ti-B master alloys and the inclusion level on the filtration performance of aluminum melt has been investigated by pilot-scale filtration tests using 50 PPi and 80 PPi filters. The inclusion level of the melt has been measured using both LiMCA and PoDFA. For 80 PPi CFF, the N20 inclusion (diameter larger than 20 μm) value in the post-filtrated melt does not increase when an ultra-high level of inclusions is introduced in the form of chips. For the melts with a low level of grain refiners (~ 0.5 kg/ton), the filtration performance of CFF is not affected by grain refiners, regardless of inclusion load. An addition of 2.0 kg/ton grain refiners reduces the filtration performance for melts with a high inclusion level, where post-filtration inclusions with the size of 15-20 µm were significantly increased. It is found, however, for the melts with an ultra-high inclusion load, the filtration performance of 80 PPi CFF is not affected by the grain refiner addition up to 2.0 kg/ton. The interactions between inclusions and grain refiner particles and the filtration mechanism have been studied by characterizing the spent filter and measuring the pressure drop during the filtration process. It is revealed that the strong adherence between oxide film with grain refiner particles dominates the grain refiner influence on the filtration performance of CFF. During the filtration process, oxide films have strong influences on the capturing of other inclusions such as oxide particles and TiB2 particles by the filter. A mechanism based on the interactions between oxide films and grain refiner particles is proposed to explain the CFF performance under the influence of grain refiner.

Research on Synthesizing Process under Ultrasound Coupling and Refining Performance of Al-Ti-C Grain Refiner

2012 ◽  
Vol 217-219 ◽  
pp. 377-381 ◽  
Author(s):  
Ying Long Li ◽  
Fu Rong Cao ◽  
Li Jin
Keyword(s):  
High Temperature ◽  
Grain Refinement ◽  
Master Alloy ◽  
Reduction Method ◽  
High Energy ◽  
Experimental Results ◽  
Reaction Synthesis ◽  
Grain Refiner ◽  
Synthesis Mechanism ◽  
Refining Performance

The microstructural characters and refining property of Al-Ti-C grain refinement alloy prepared by ultrasound coupling method were studied by analytical means such as SEM, and the reaction synthesis mechanism of Al-Ti-C grain refinement was discussed. Experimental results show that the Al-Ti-C alloy refiner using “thermite reduction method” under high-energy ultrasound was prepared experimentally. Its microstructure character is that master alloy has smaller size of TiC, its quantities are larger and are dispersed. Melt reaction is generally that the source of titanium releases Ti atoms under high temperature of ultrasonic. Ti atoms react with aluminum to generate TiAl3, and react with carbon to generate TiC.

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.

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.

scholarly journals A study on grain refinement of AZ91E magnesium alloy with Al-5TiB₂, AI-Al₄C₃ and ZnO additions

2021 ◽  
Author(s):  
Kenneth Lee
Keyword(s):  
Grain Refinement ◽  
Base Alloy ◽  
Hot Tearing ◽  
Mg Alloys ◽  
Grain Refiner ◽  
Dendritic Microstructure ◽  
Refinement Efficiency ◽  
Average Grain Size ◽  
Refinement Mechanism ◽  
Environmentally Safe

There is great interest in increasing the use of magnesium (Mg) alloys in transportation applications to reduce weight. The use of these alloys would increase if their strength and castability were improved. Through grain refinement, it is possible to achieve significant improvement in specific mechanical properties such as strength and hardness. For aluminum (A1)-containing Mg alloys, a commonly used grain refiner is hexachloroethane (C₂Cl₆). Though effective, C₂Cl₆ use releases harmful chlorinated hydrocarbons. It is therefore desired to find novel grain refiners that are effective and environmentally safe. This thesis focused on the grain refinement of AZ9lE alloy with three refiners: Al-5TiB₂, Al-A1₄C₃ and ZnO. The refiners were chosen due to their known grain refinement efficiency in low-Al Mg or Mg-Zn alloys. Castings with each refiner were made in graphite molds to establish i) the optimum addition levels to achieve the smallest average grain size and ii) the effect of holding time on fading of grain refinement efficiency. These castings ere used to collect thermal data and sectioned for microscopy and hardness testing. Castings were also made with the optimum parameters in a permanent mold specifically designed to investigate hot tearing susceptibility. The results indicated that all three additions enabled grain refinement of the base alloy, and no fading of grain refiner efficiency was observed. These refiners transformed the coarse dendritic microstructure in AZ9lE to one that was equiaxed and globular. At optimal levels, the refinement mechanism was heterogeneous nucleation. Also, hot tearing was significantly decreased with all refiners except for ZnO. The excess Zn from ZnO addition led to an increase in the freezing range, thus increasing the hot tear severity. The hardness of AZ9lE did not increase with ZnO addition as it did with the other two refiners.

scholarly journals Grain Refinement of AZ91 Magnesium Alloy Induced by Al-V-B Master Alloy

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1333 ◽  
Author(s):  
Wang Chang ◽  
Yanping Shen ◽  
Yueying Su ◽  
Long Zhao ◽  
Yunhu Zhang ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Comparative Study ◽  
Grain Refinement ◽  
Master Alloy ◽  
Al Alloys ◽  
Az91 Alloy ◽  
Grain Refiner ◽  
Az91 Magnesium Alloy ◽  
Master Alloys ◽  
Az91 Magnesium

It has long been recognized that grain refinement of Mg-Al alloys is difficult, although various methods have been tried. In the present paper, a novel grain refiner, Al-3.4V-1B master alloy, has been developed to refine the as-cast AZ91 alloy. A comparative study on grain refinement effects of Al-3.4V-1B, Al-5V, and Al-3Ti-1B master alloys was performed under the same solidification conditions. It is shown that Al-3.4V-1B master alloy not only has significant grain refinement ability, but also keeps stable anti-fading capacity with holding time up to 2 h. Based on the analysis of grain refinement, VB2 particles introduced by Al-3.4V-1B master alloy are the heterogeneous nuclei for AZ91 alloy.

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