The Grain Refinement of Al-Si Alloys and the Cause of Si Poisoning: Insights Revealed by the Interdependence Model

2014 ◽  
Vol 794-796 ◽  
pp. 161-166 ◽  
Author(s):  
Mark A. Easton ◽  
Arvind Prasad ◽  
David H. St. John
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Master Alloy ◽  
Cost Effective ◽  
Optimum Level ◽  
Grain Sizes ◽  
Relative Contribution ◽  
Master Alloys ◽  
Effective Use ◽  
Special Case

Recent work has extended the Interdependence Model to the prediction of grain size of aluminium alloys when refined by Al-Ti-B master alloys. The relative contribution of Ti solute and TiB2 particles to the as-cast grain size was determined indicating the optimum level of addition required to provide cost effective use of master alloy. This paper quantifies the effect of Al5Ti1B master alloy additions on the grain size of Al-Si alloys. The Al-Si system is a special case where additions of Si above a few percent poison grain refinement resulting in larger grain sizes. Consideration of the complicating effect of Si poisoning on the prediction of the grain size of these alloys and possible approaches to dealing with these complications are 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 Effect of cooling rates of production process of Al-3%B-3%Sr master alloy on grain refinement and eutectic modification efficiency in cast A356 alloy

2018 ◽  
Vol 192 ◽  
pp. 01036
Author(s):  
Krittee eidhed ◽  
Phisith muangnoy
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Master Alloy ◽  
Eutectic Silicon ◽  
A356 Alloy ◽  
Holding Time ◽  
Experimental Result ◽  
Cooling Rates ◽  
Eutectic Modification ◽  
Master Alloys

In this paper, size and morphology of the grain refiner and modifier particles in the Al-3%B-3%Sr master alloy production by using different cooling rates were investigated. Two Al-3%B-3%Sr master alloys were produced with 0.2 and 10°C/s, respectively. The grain refinement and eutectic modification efficiency of the Al-3%B-3%Sr master alloy were tested in casting process of A356 alloy by addition of 4wt.% and holding times for 10-120 min. The experimental result showed that microstructure of the M1 alloy (Slow cooling) consisted of larger solidified particles of AlB2, SrB6 and Al4Sr in the matrix of α-Al compared to the M2 alloy (Rapid cooling). The addition of the M1 alloy in cast A356 alloy, it was found that small grain size and fully modify eutectic silicon were obtained from the holding time in a range of 10-60 min. While the addition of M2 alloy, a small grain size was achieved in shorter holding time in a range of 10-30 min but the eutectic silicon was partly modify. From the thermal analyzed result, solidification of un-modified A356 alloy was changed after addition of Al-3%B-3%Sr master alloy. It was clearly observed that both the undercooling of nucleation and eutectic reaction was reduced and the solidification time was shifted to longer.

scholarly journals Development of New Oxide Based Master Alloys and their Grain Refinement Potency in Aluminium Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 23-28 ◽  
Author(s):  
Vadakke Madam Sreekumar ◽  
N. Hari Babu ◽  
Dmitry G. Eskin ◽  
Z. Fan
Keyword(s):  
Grain Size ◽  
Cooling Rate ◽  
Grain Refinement ◽  
Master Alloy ◽  
Aluminium Alloys ◽  
Al Alloys ◽  
Ultrasonic Cavitation ◽  
Size Reduction ◽  
Refinement Efficiency ◽  
Master Alloys

In this study, grain refinement efficiency of a new oxide master alloy based on MgAl2O4 was demonstrated in Al alloys. The grain size of the reference alloy was reduced by 50-60% with the addition of the master alloy and introduction of ultrasonic cavitation. While cooling rate has an influence on the grain size reduction, higher levels of addition of master alloy was found to be not effective in further reducing the grain size.

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.

Effect of Composite Master Alloy on Mechanical Properties and Electrochemical Corrosion of ZL101 Alloy

2013 ◽  
Vol 749 ◽  
pp. 407-413
Author(s):  
Hong Xu ◽  
Xin Zhang ◽  
Ji Ping Ren ◽  
Min Peng ◽  
Shi Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Grain Refinement ◽  
Master Alloy ◽  
Mass Fraction ◽  
Electrochemical Corrosion ◽  
Corrosion Performance ◽  
Obvious Effect ◽  
Mechanical Properties And Corrosion

The mechanical properties and corrosion performances of the ZL101 alloy modified by the composite master alloy were investigated. The results showed that the master alloy had not only obvious effect of grain refinement, but also a significant role in refining dendrite grain of ZL101 alloy. The grain size decreased dramatically from 150μm to 62μm when the addition of composite master alloy is up to 0.5%(mass fraction) and the temperature is 720 for 30 minutes,. Its tensile strength and elongation increased by 27% and 42% respectively. The grain refinement of ZL101 alloy decreased its corrosion performance. The morphology of Si changed into globular from needle modified by NaF, instead of AlTiB.

A High Effective and Low-Cost Modifier for Hypereutectic Al-Si Alloys

2013 ◽  
Vol 721 ◽  
pp. 282-286
Author(s):  
Guang Hui Qi
Keyword(s):  
Grain Size ◽  
Master Alloy ◽  
Low Cost ◽  
Environment Pollution ◽  
Casting Method ◽  
Good Future ◽  
Primary Si ◽  
Average Grain Size ◽  
Master Alloys

In order to settle environment pollution and provide a high effective and low-cost modifier for refining the primary Si in hypereutectic Al-Si alloys, Al-Fe-P master alloys containing 2.0~5.0% phosphorus have been invented by casting method. The Al-Fe-P master alloys can be conveniently produced and an excellent modification can be obtained by adding 0.3~0.8wt% Al-Fe-P master alloy in Al-Si alloys containing 12%-25% Si at a relatively lower modifying temperature. The number of primary Si increases obviously and the average grain size of primary Si decreases largely, less than 50μm. Furthermore Al-Fe-P master alloys have many advantages, such as low cost, convenient operation technology, no pollution, stable and long-term modification effect, easy storage and etc. Al-Fe-P master alloys have overcome the shortages of current modifier and have a good future for hypereutectic Al-Si alloy modification.

Influence of Reaction Temperature for the Manufacturing of Al-3Ti and Al-3B Master Alloys and their Grain Refining Efficiency on a Al-7Si Alloy

2007 ◽  
Vol 29-30 ◽  
pp. 111-115 ◽  
Author(s):  
S.A. Kori ◽  
V. Auradi
Keyword(s):  
Size Distribution ◽  
Grain Refinement ◽  
Reaction Temperature ◽  
Master Alloy ◽  
Induction Furnace ◽  
Grain Refining ◽  
Refining Efficiency ◽  
Master Alloys ◽  
Halide Salts ◽  
Titanium Fluoride

In the present work binary Al-3Ti and Al-3B master alloys were prepared at different reaction temperatures in an induction furnace by the reaction of halide salts like potassium fluoborate and potassium titanium fluoride with liquid molten Al. The indigenously developed master alloys were used for grain refinement studies of Al-7Si alloy and evaluated for their grain refining ability by CACCA studies. The present results suggest that, the reaction temperature influences the size, size distribution and morphology of the intermetallic (Al3Ti in Al-3Ti, and AlB2/AlB12 in Al-3B) particles present in Al-3Ti and Al-3B master alloys. Grain refinement studies of Al-7Si alloy reveal that, Al-3Ti and Al-3B master alloys prepared at 8000C-60 min. have shown better grain refining efficiency on Al- 7Si alloy when compared to the master alloys prepared at 9000C-60 min and 10000C-60 min respectively. In addition, B-rich Al-3B master alloy shows efficient grain refinement than Ti rich Al- 3Ti master alloy.

The Effect of Manganese on the Grain Size of Commercial AZ31 Alloy

2005 ◽  
Vol 488-489 ◽  
pp. 139-142 ◽  
Author(s):  
Peng Cao ◽  
David H. StJohn ◽  
Ma Qian
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Master Alloy ◽  
Electron Microprobe ◽  
Az31 Alloy ◽  
Long Period ◽  
Intermetallic Particles ◽  
Nucleation Sites

The effect of manganese on grain refinement of a commercial AZ31 alloy has been investigated using an Al-60%Mn master alloy splatter as an alloying additive at 730 °C in aluminium titanite crucibles. It is shown that grain refinement by manganese is readily achievable in AZ31. Electron microprobe analyses reveal that prior to the addition of extra manganese the majority of the intermetallic particles found in AZ31 are of the Al8Mn5 type. However, after the addition of extra manganese in the range from 0.1% to 0.8%, the predominant group of intermetallic particles changes to the metastable AlMn type. This leads to a hypothesis that the metastable AlMn intermetallic particles are more effective than Al8Mn5 as nucleation sites for magnesium grains. The hypothesis is supported by the observation that a long period of holding at 730 °C leads to an increase in grain size, due probably to the transformation of the metastable AlMn to the stable Al8Mn5. The hypothesis has also been used to understand the mechanism of grain refinement by superheating.

The Characteristic Grain Size and the Compressive Strength of Ice Containing a Bimodal Distribution of Grain Sizes

1989 ◽  
Vol 111 (1) ◽  
pp. 61-62
Author(s):  
E. M. Schulson ◽  
J. L. Laughlin
Keyword(s):  
Grain Size ◽  
Compressive Strength ◽  
Grain Refinement ◽  
Bimodal Distribution ◽  
Grain Sizes ◽  
Freshwater Ice ◽  
Polycrystalline Ice

The purpose of this communication is to show through experiment that the compressive strength of polycrystalline ice, which contains a bimodal distribution of grain sizes, can be expressed in terms of a characteristic grain size. The work was performed in response to an awareness that grain refinement strengthens both columnar [1] and granular [2] freshwater ice deformed under compression, and that ice formed naturally often contains grains of more than one size. A detailed discussion is given elsewhere [3].

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