Refinement of primary Si in Cu-50Si alloys with novel Al-Zr-P master alloy

In this article, a novel Al-6Zr-2P master alloy with ZrP particles was successfully synthesized, and the refining performance of this novel master alloy for the primary Si in Cu-50Si alloys was also investigated. By means of the fracture plane observation, it is found that the ZrP phase would precipitate first in the solidification pro- cess, and then, the ZrAl3 phase grows around them. Fur- thermore, it is observed that the refining effect can be remarkably improved by changing the addition sequence of the raw materials. After the melting of commercial Cu, the 2.0 wt% Al-6Zr-2P master alloy and crystalline Si were added in sequence, and the mean size of the primary Si in Cu-50Si alloy can be significantly refined from 255.7 to 75.3 gm. Meanwhile, the refining mechanism was dis- cussed in detail.

Aluminothermic Reduction of K_2ZrF_6 for Preparation of Al-Zr Master Alloy

This paper summarizes a process for the preparation of Al5%Zr master alloy by the reduction of K2ZrF6 with aluminium. The reduction in grain size of aluminium by addition of known quantity of master alloy is also studied.

Al-Si-P master alloy and its modification and refinement performance on Al-Si alloys

An Al-Si-P master alloy has been developed by an in-situ reaction and the electron probe microanalyzer （EPMA） results show that there are many pre-formed AlP particles contained in the master alloy. Silicon introduced into the system plays an important role in remarkably improving the distribution and content of AlP particles due to their similar crystal structure and lattice parameters. ZL109 alloys have shown fast modification response to the addition of 0.5% Al-15Si-3.5P master alloy at 720℃, with a mass of primary Si precipitating in size of about 15 μm. Also, coarse primary Si grains in AI-30Si alloy can be refined dramatically from 150 μm to 37 μm after the addition of 2.0% Al-15Si-3.5P master alloy at 850℃. The P recovery of the Al-15Si-3.5P master alloy is much higher than that of a Cu-8.5P master alloy due to the pre-formed AlP particles.

INFLUENCE OF Al-5Ti-1B MASTER ALLOY ON MICROSTRUCTURE AND DAMPING CAPACITY OF ZA27 ALLOY

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Influences of Preparation Conditions and Melt Treatment Procedures on Melt Treatment Performance of Al-5Ti-B and Al-10Sr Master Alloys

The influences of preparation conditions of Al-5Ti-B （as-cast and hot-rolled） and Al-10Sr （as-cast and hotextruded） and melt treatment procedures on the grain refinement and modification performance of A356 alloy are experimentally studied. For the two master alloys, the 50% reduction is sufficient to meet the demands of the efficient grain refinement and modification of A356 alloy. When Al-STi-B is introduced into the melt prior to degassing, the grain refinement efficiency of Al-5Ti-B will be greatly increased due to the better dispersity of TiB2 particles. Al-5Ti-B master alloy is less prone to affect the modification effect of Al-10Sr when they are used together.

Refining Effect of a New Al3Ti1B1RE Master Alloy on Al Sheets Used for Can Manufacture and Behavior of Rare Earths in Master Alloy

The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behavior of mixed rare earths in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the refining effect of the refiner on the material has superiority over foreign or domestic Al5Ti1B refiner, and the refiner still retains its refining ability for 6 h after adding it to molten Al, thus improving the strength and plasticity of the material remarkably. The excellent refining effect and stability of AlTiBRE refiner result from that RE can lower the surface energy of molten Al and improve the wetting characteristics of molten Al on refinement nuclei such as TiAl 3, TiB 2, etc., thus giving full play to the effect of heterogeneous nucleation and impeding the congregating tendency of TiB 2 phase in molten Al. At the same time, RE gathering in front of solid/liquid interface are also easy to cause composition supercooling in molten Al, thus impeding the growth of α Al grains and promoting α Al nucleation on refinement nuclei. In addition, RE also play certain role in purification and grain refinement, or modification, especially their effect of purification can improve the metallurgical quality of AlTiBRE master alloy.

Role of C and Fe in Grain Magnesium Alloy by Al-C Refinement of an AZ63B Master Alloy

In this study, grain refining effect of Al-1.5℃ master alloy was examined on an AZ63B magnesium alloy, and the refining mechanism was studied through investigating the role of C and Fe in this process. The results show that addition of Al-1.5℃ master alloy leads to significant decrease of the mean grain size from about 270μm to 50μm at the center of the AZ63 alloy ingot. Grain refinement by carbon addition is mainly due to the heterogeneity nucleation on the Al-, C-, O-, Fe- and Mn-rich particles, but not constitutional undercooling caused by the carbon solute element. Fe plays an important role in the formation of the nucleating particles, but not acts as an inhibiting element.

Improvement in grain refinement efficiency of Mg-Zr master alloy for magnesium alloy by friction stir processing

Previous studies have proved that the zirconium(Zr)alloying and grain refining performance of a Mg-Zr master alloy on Mg alloy is closely related to the distribution of Zr particle size,and a Mg-Zr master alloy with more Zr particles in size range of 1-5μm exhibits a better refining efficiency.In this paper,friction stir processing(FSP)was used to modify the Zr particles size distribution of a commercially available Mg-30 wt.%Zr master alloy,and the subsequent grain refinement ability was studied by trials on a typical Mg-3Nd-0.2Zn-0.6Zr(wt.%,NZ30K)alloy.It is found that plenty of large Zr particles in the as-received Mg-30%Zr master alloy are broken by FSP.Grain refinement tests reveal that the refining efficiency of Mg-30%Zr alloy is significantly improved by FSP,which is attributed to the better distribution of Zr particles.The refinement effect by adding 0.6%FSP-ed Mg-30%Zr is approximately equivalent to that by adding 1.0%as-received Mg-30%Zr.Due to the easy and convenient operation of FSP,this study provides a new method to develop a more efficient Mg-Zr refiner.

Effect of cooling rate on morphology and type of vanadium-containing phases in Al-10V master alloy

Effects of cooling rates on the morphology, sizes and species of primary vanadium-containing phases in Al-10V master alloys were investigated. The results show that the primary vanadium-containing phases with different morphologies and compositions present in Al-10V master alloys at different cooling rates with the pouring temperature of 1,170 °C. When the Al-10V master alloy is solidified in the refractory mold at a cooling rate of 2 °C·s-1, the vanadium-containing phases are mainly plate-like Al10V phases, with the average size of 100.0 μm in the center and 93.2 μm at the edge of the ingot. When the master alloy is solidified in the graphite mold at a cooling rate of 24.3 °C·s-1, the primary vanadium-containing phases are dendritic Al3V phases, with the average length of 297.0 μm for the first dendrite in the center and 275.0 μm at the edge of the ingot. The secondary dendrite arm spacing (SDAS) is 9.5 μm in the center and 9.3 μm at the edge of the ingot, respectively. When the solidification is carried out in the copper mould at a cooling rate of 45.7 °C·s-1, the primary vanadium-containing phases are also Al3V phases but with smaller size, compared with that prepared at the cooling rate of 24.3 °C·s-1. As a result, the average length is 190.0 μm for the first dendrite in the center and 150.0 μm at the edge of the ingot. The SDAS is 9.8 μm in the center and 4.4 μm at the edge of the ingot, respectively.

Grain refinement of AZ31 magnesium alloy by Al-Ti-C-Y master alloy

Al-Ti-C-Y master alloy was prepared by combining SHS technique and melting-casting method. The microstructure of master alloy and its grain-refining effect on AZ31 alloy were investigated by means of OM, XRD, SEM and EDS. Experimental results indicated that the prepared master alloy consisted of α-Al, TiAl3, TiC and Al3Y phases, and exhibited good grain-refining performance of AZ31 alloy. Morphology of α-Mg changed from coarse dendritic to free equiaxed and the average grain size of α-Mg matrix reduced from the original 580 to 170 μm after adding 1.0 wt.% master alloy. The grain refining efficiency of Al-Ti-C-Y master alloy on AZ31 alloy was mainly attributed to heterogeneous nucleation of TiC particles and grain growth restriction of Al-Y compound or TiC at grain boundaries.

Preparation of Al-Sr Master Alloy in Aluminum Electrolysis Cell

Al Sr master alloy was prepared by using liquid aluminum cathode and a mixture of Na 3AlF 6 - SrCO 3 as the basic molten salt electrolyte in a laboratory electrolysis cell.The effects of electrolyte composition,electrolysis temperature,cathodic current density and the electrolytic duration on Sr content of Al Sr alloy were studied.Through laboratory experiments,the parameters for smooth electrolytic reaction were proposed.

STUDY OF THE NUCLEATION MECHANISM OF α-Al GRAINS AFTER ADDITION OF Al-Ti-B MASTER ALLOYS

Nucleation sites of α-Al grains after addition of an Al-Ti-B master alloy into pure aluminium have been investigated using EPMA. The results show that either TiAl3 or boride particales can nucleate α-Al grains. But the number of TiAl3 nucleants is reduced with the holding time prolonged and the boride-nuclei are increasing gradually. Based on these results, a new refining method, adding molten Al-Ti-B into commercially pure aluminium, which has a quicker and better refining efficiency is presented.

Quality assessment of aluminum-based grain refining master alloys

Based on some theoretical and practical approaches, the main stages of the quality assessment of aluminum-basedgrain refining master alloys have been revealed. Methods for the quality improvement of Al-Ti and Al-Ti-B grain refinershave been described.

Influence of Al-5Ti-1B master alloy addition on the grain size of AZ91 alloy

The mechanical properties of castings depend on the grain size.There is evidence that titanium and boron(Al-5Ti-1B master alloy)affect the grain size of magnesium alloys.Here,the influence of the addition of 0-1 wt.%of Al-5Ti-1B master alloy on the grain size of AZ91 magnesium alloy was investigated.Melting of the alloy was performed in steel and corundum crucibles.To study the effect of cooling rate on grain size,cylindrical samples were cast in steel and fireclay molds.The Al-5Ti-1B master alloy addition did not change the phase composition of the AZ91 alloy.This study demonstrates that the addition of Al-5Ti-1B did not contribute to the grain refinement of the AZ91 alloy,but rather led to its coarsening for samples cast in both the steel and fireclay molds.Increasing the holding time after the addition of the Al-5Ti-1B master alloy from 15 to 110 minutes also did not lead to significant grain coarsening.The mechanical properties of the AZ91 alloy samples slightly improved after Al-5Ti-1B addition.

A new development of Al-Ti-C grain refining master alloys

Al Ti C master alloys have been prepared with a novel production method. A combination of X ray phase analysis, SEM and EDS was used to examine the phases and microstructures of the master alloys. The master alloys have block like Al 3Ti particles and submicron size TiC X with X ranging from 0.49 to 0.78 and show excellent grain refining performance for commercially pure aluminum. Titanium carbides were observed at the crystallization centers in refined castings.

Effect of Y Addition on Microstructure and Constituent Phases of Al-Ti-C Master Alloy

Al-Ti-C master alloy was prepared by SHS (Self-propagating High temperature Synthesis)-melting technique. Effect of yttrium addition level on the microstructures of the master alloy was studied by XRD, SEM and EDS. The experimental results show that the addition of 1.0% Y is beneficial to the formation of TiC particles; Al-Ti-C-1.0Y consists of rod-like and blocky TiAl3, TiC, Al3Y and α-Al matrix. Y is found around TiC particles in Al-Ti-C-0.5Y master alloy while blocky (AlTiY) phase appears in Al-Ti-C-1.0Y master alloy. Al3Y with dendritic morphology and small blocky Al2Y except for TiC are found in Al-Ti-C-2-0Y master alloy.

Grain reinement limit of commercial pure Al inoculated by Al-Ti-C(B) master alloys

The grain refi nement limits of commercial pure Al inoculated by Al-5Ti-1B, Al-5Ti-0.25C and Al-5Ti-0.3C-0.2B master alloys were studied, and the infl uence of melting temperature on the grain refi ning performance of these three master alloys was investigated using a high scope video microscope(HSVM), a fi eld-emission scanning electron microscope(FESEM), an electron probe micro-analyzer(EPMA) and X–ray diffraction(XRD) method. Results show that there is a grain refi nement limit of commercial pure Al refi ned by these three master alloys; with the same addition level of 1.5% under the present experimental conditions, the grain refi nement limits(smallest average grain size) of commercial pure Al refi ned by Al-5Ti-1B, Al-5Ti-0.25C and Al-5Ti-0.3C-0.2B master alloys are 50 μm, 80 μm and 80 μm, respectively. In addition, with an increase in the melting temperature of the pure Al, the grain refi ning performance of Al-5Ti-1B and Al-5Ti-0.25C master alloys decreases, but the grain refi ning performance of Al-5Ti-0.3C-0.2B changes little.

Preparation of Master Alloy Cu－Sr by Molten Salt Electrolysis with Copper Consumable Cathode

The influence of electrolyte composition and temperature. cathodie current density as well as someadditives on preparation process of alloy Cu-Sr by molten salt electrolysis with consumable cathode was stu-died in laboratory. Under optimum conditions determined experimentally. the current efficiency amountedto 70% and the master alloy contained 61% Sr After vacuum distillation or the cathodic product, metallicSr of 98% purity was obtained.

Effect of AlP master alloy on grain refinement of primary silicon in eutectic Al-Si alloys

To obtain the finer primary silicon crystals, the proprietary Al-P masteralloy was adopted to modify the eutectic Al-Si alloys and the most suitable modification process wasmade in the experiments. The SEM (Scanning Electron Microscope) and DSC (Differential ScanningCalorimeter) analysis indicate that the Al-P modifier has more advantages over Cu-P and Fe-Pmodifier in easily addition, no elemental alteration and less undercooling of primary silicon'ssolidification, which suggests the Al-P master alloy is an effective modifier of eutectic Al-Sialloys.

Effects of Al-10Sr master alloys on grain refinement of AZ31 magnesium alloy

The effects of Al-10Sr master alloys on grain refinement of AZ31 magnesium alloy were investigated,and the refinement efficiency of different Al-10Sr master alloys(commercial,solubilized,rolled and remelted+rapidly cooled)was compared and analyzed.The results indicate that the morphology and size of Al4Sr phases in the microstructures of different Al-10Sr master alloys,are of great difference.For the commercial Al-10Sr master alloy,the Al4Sr phases evolve from coarse block shape to relatively fine block shape after being dissolved at 500 ℃ for 4 h and followed by water quenching;but after being rolled at 300 ℃ for 50% reduction or remelted and followed by rapid cooling,the Al4Sr phases mainly exhibit fine granule and fibre shapes.In addition,the different Al-10Sr master alloys can effectively reduce the grain size of AZ31 magnesium alloy,but their refinement efficiency is different.The refinement efficiency of the Al-10Sr master alloy obtained by remelting and rapid cooling is the best,then the rolled,solubilized and commercial Al-10Sr master alloys are in turn.The difference of refinement efficiency for different Al-10Sr master alloys may be related to the dissolution rates of Al4Sr phases with different morphologies and sizes in the melt of AZ31 magnesium alloy.