Effect of Oxygen on the β-Grain Size of Cast Titanium

2010 ◽  
Vol 654-656 ◽  
pp. 1472-1475 ◽  
Author(s):  
Michael J. Bermingham ◽  
Stuart D. McDonald ◽  
Matthew S. Dargusch ◽  
David H. StJohn
Keyword(s):  
Grain Size ◽  
Titanium Alloys ◽  
Recent Work ◽  
Grain Refinement ◽  
Growth Restriction ◽  
Restriction Factor ◽  
Grain Refining ◽  
Grain Refiner ◽  
Growth Restriction Factor ◽  
Effect Of Oxygen

Grain refinement of titanium alloys during solidification is believed to have many benefits for processing and properties. Recent work has emphasized the importance of solute elements in grain refining cast titanium and it was demonstrated that the growth restriction factor is useful for predicting the grain refining effectiveness of solute elements in titanium. Despite oxygen being the major impurity element present in titanium alloys and having been previously identified as a theoretical growth restricting solute, its effect as a β-grain refiner is still unexplored. This paper investigates the effect of oxygen on the grain size in cast titanium alloys.

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.

Latest Developments in Understanding the Grain Refinement of Cast Titanium

2009 ◽  
Vol 618-619 ◽  
pp. 315-318 ◽  
Author(s):  
Michael J. Bermingham ◽  
Stuart D. McDonald ◽  
Matthew S. Dargusch ◽  
David H. StJohn
Keyword(s):  
Grain Size ◽  
Titanium Alloys ◽  
Grain Refinement ◽  
Grain Refining ◽  
Current State ◽  
State Of Research

Grain refinement of cast titanium alloys is believed to have many benefits. However, literature on how to control and manipulate β-grain size during the solidification of cast components is scarce. This paper discusses the current state of research in grain refining practices in cast titanium alloys.

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.

scholarly journals Taguchi Approach for Optimization of Parameters that Effect Grain Size of Cast A357 Alloy

2017 ◽  
Vol 17 (4) ◽  
pp. 35-42 ◽  
Author(s):  
M. Çolak ◽  
D. Dışpınar
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Dendritic Structure ◽  
Grain Refining ◽  
Grain Refiner ◽  
A357 Alloy ◽  
Effective Factor ◽  
Alloy Type ◽  
Eutectic Modification ◽  
Strength And Ductility

AbstractGrain refining and modification are common foundry practice for improving properties of cast Al-Si alloys. In general, these types of treatments provide better fluidity, decreased porosity, higher yield strength and ductility. However, in practice, there are still some discrepancies on the reproducibility of the results from grain refining and effect of the refiner’s additions. Several factors include the fading effect of grain refinement and modifiers, inhomogeneous dendritic structure and non-uniform eutectic modification. In this study, standard ALCAN test was used by considering Taguchi’s experimental design techniques to evaluate grain refinement and modification efficiency. The effects of five casting parameters on the grain size have been investigated for A357 casting alloy. The results showed that the addition of the grain refiner was the most effective factor on the grain size. It was found that holding time, casting temperature, alloy type and modification with Sr were less effective over grain refinement.

scholarly journals Grain Refining of Aluminium and 6063 Alloys Using Al-V Alloy Containing Al3V Intermetallic Compound

2021 ◽  
Author(s):  
Gamal Mohamed Attia MAHRAN ◽  
Abdel-Nasser Mohamed OMRAN
Keyword(s):  
Intermetallic Compound ◽  
Grain Refinement ◽  
Master Alloy ◽  
Aluminium Alloys ◽  
Vanadium Content ◽  
Restriction Factor ◽  
Pure Aluminium ◽  
Grain Refining ◽  
Grain Refiner ◽  
Different Levels

The grain refinement of aluminium alloys is one of the important processes in various industrial fields. This work aims to use aluminium-vanadium (Al-V) master alloy as a new grain refiner for grain refinement of aluminium alloys. The new refiner was prepared by reduction of vanadium pentoxide V2O5 using molten aluminium, then it was examined using SEM, EDS, XRD, and optical microscopy. The findings of these tests indicated that the developed master alloy contains blocky-shaped particles evenly distributed within the aluminium matrix Al3V in the form of an intermetallic compound. Different levels of vanadium content were examined (3.5, 5.6, and 8.3) as grain refiners for commercial pure Al and 6063 alloys. It was found that the grain size was decreased from 2000 to 320 mm for commercial pure aluminium and decreased from 1500 to 300 mm for 6063 alloys. The best results were obtained by using vanadium content of 0.03 wt.% in the refined alloy and a holding time of 3 min. Based on the gross restriction factor (GRF), the new grain refiner Al-V master alloy performed well at vanadium contents more than 0.02 wt.% in the refined alloy.  

scholarly journals Effect of Melt Temperature on the Effectiveness of the Grain Refining in Al-Si Castings

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
A. M. Samuel ◽  
S. S. Mohamed ◽  
H. W. Doty ◽  
S. Valtierra ◽  
F. H. Samuel
Keyword(s):  
Grain Size ◽  
Dendritic Structure ◽  
Grain Refining ◽  
Liquid Temperature ◽  
Grain Refiner ◽  
Dendrite Morphology ◽  
Melt Temperature ◽  
Strong Affinity ◽  
Rounded Form ◽  
Molten Liquid

The results inferred from the present work show that Al3Ti phase has a strong affinity to react with silicon (Si) in the molten alloy leading to formation of (Al,Si)3Ti phase instead. This reaction is independent of the grain refiner type. The molten liquid temperature would change its morphology from platelets at 750°C into dendritic structure at 950°C. It has also been observed that (Al,Si)3Ti phase platelets precipitate within the α-aluminum dendrites, whereas TiB2 or AlB2 particles are released into the surrounding interdendritic regions. Introduction of the grain refiner, regardless its type, would cause change in the α-aluminum dendrite morphology from an elongated to a more rounded form. The results also reveal that addition of 100 ppm B will reduce the initial grain size by ∼85% which is more than the effect of addition of 0.2%Ti in the form of Al-10%Ti (about 65%). Elimination of undercooling is important to obtain the maximum grain refining effect.

Practical Considerations on the Application of Ultrasonic Treatment to Mg-Al Shape Castings

2013 ◽  
Vol 765 ◽  
pp. 255-259
Author(s):  
Eraldo Pucina ◽  
Geoff de Looze ◽  
Dacian Tomus ◽  
Mark A. Easton ◽  
Andreas Schiffl ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Ultrasonic Treatment ◽  
Solidification Front ◽  
Al Alloys ◽  
Grain Refining ◽  
Fine Grain ◽  
Effective Form

This paper investigates the use of ultrasonic treatment on the grain refinement of Mg-Al alloys in castings similar to commercial gravity castings. It shows that it is a very effective form of grain refinement but it is limited spatially and by the advancing solidification front if partially-solidified product is washed into the die. It was found that the best way to obtain a homogeneous fine grain size through-out the casting was to combine a grain refining addition, SiC, with ultrasonic treatment during the initial stages of solidification.

scholarly journals Synergistic Effect of La and TiB2 Particles on Grain Refinement in Aluminum Alloy

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 600
Author(s):  
Lili Zhang ◽  
Yan Song ◽  
Linjie Yang ◽  
Jiuzhou Zhao ◽  
Jie He ◽  
...  
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Synergistic Effect ◽  
Grain Refinement ◽  
Grain Refining ◽  
Average Grain Size ◽  
Calculation Results ◽  
La Addition ◽  
Tib2 Particles ◽  
Addition Level

Synergistic effect of TiB2 (in form of Al-5Ti-1B) and La on grain refining results in Al-2Cu alloy was investigated. α-Al grains are significantly refined by Al-5Ti-1B. When trace La is added to the melt, further refinement is exhibited. Average grain size and nucleation undercooling of α-Al reduce first and then almost remain unchanged with La addition. Satisfactory grain refining result achieves when La addition level reaches 600 ppm. When more than 600 ppm La is added to the melt, La-rich particles form and the effect of solute La left in matrix on the microstructure almost no longer changes. Theoretical calculation results demonstrate that solute La segregates to Al melt/TiB2 particles interface along with Ti and Cu prior to α-Al nucleation and the synergistic effect of La and TiB2 particles on grain refinement mainly attributes to the enhancement in the potency of TiB2 particles to heterogeneously nucleate α-Al by trace La addition.

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