Papers by Keyword: High Purity Aluminium

Abstract: The effects of final forging temperatures on deformability and structure evolution of high purity aluminum during multi-directional forging process were investigated. The results showed that increasing the initial forging temperature is beneficial for controlling the sample shape in the initial forging passes. Recrystallization during the initial forging passes improves the deformability of the sample in the following low-temperature forging processes. An X-shape fine grain zone is formed in the sample due to the inhomogeneous deformation of multi-directional forging process. When the forging pass is 6, the final forging temperature has an important influence on the grain size in the fine grain zone. The grain size decreases from 302 μm to 60 μm with the final forging temperature decreasing from 310 °C to 65 °C. The X-shape fine grain zone caused by the inhomogeneous deformation cannot be eliminated by increasing the final forging temperature (even higher than the recrystallization temperature of high purity aluminium).

Abstract: The new extrusion route of ECAP which is called route 135 was put forward in this paper. The grain refinement of the traditional extrusion route B_C and the new route of ECAP process in 99.9995% (5N5) high purity aluminum was compared using a die with a channel-intersection angle 90°. It was found through experiment that, the grain was very coarse in the cast ingot of 5N5 high purity aluminum, and the average grain size is about 60mm. High purity aluminum processed by one pass ECAP was refined notably, and average grain size is about 1000 μm. After two ECAP passes, the average grain size is 200μm with route B_C, while it is less than 50μm with route 135. The refinement of two passes of route 135 is equivalent to the refinement of eight passes of route B_C. It indicates that the route 135 is more effective than route B_C. TEM micrograph of 5N5 high purity Al with different ECAP pass under route B_C and route 135 was studied.

Abstract: High purity aluminium has been successfully rheocast using the CSIR-RCS system combined with high pressure die casting. Analysis of the as-cast microstructure by SEM and EBSD revealed the presence of in-grain substructures. These morphological features show that the overall growth mode of the globular grains during rheocasting is planar, but the presence of these features indicates that the solidification mode is cellular at some stages during the slurry production process. Cellular solidification is associated with unstable growth at the solid-liquid interface and is initiated and exacerbated by solute gradients between the melt and the newly formed solid. This high purity alloy exhibits the same cellular growth, indicating that even minor solute variations have an effect on the stability of the solid-liquid interface and, hence, the mode of solidification during semi-solid rheocasting.

Abstract: The Self-Organizing Anodic Aluminium Oxide(AAO) Template Is Widely Used to Construct the Nanomaterials. but the AAO Film Is Very Thin and Brittle, the AAO Templates Are Easily Been Destroied when Widening and Opening the Nanopores. the Nanorods/wires Constructed by this Template Likely Aggregate because of the High Activity of Nano-Surface at Short Range. this Paper Proposed a Novel Image of AAO Template in which Several Nanopores Combined Together to Form a Large Open Holes without Widening the Cells and Opening Barrier Layers. the Electronic Aluminium Foils with 99.99% Purity Is Anodized in Phosphoric Acid by Two-Steps, then Polarized under a Negative Voltage in the Kcl Solution. the Result of Experiment Demostrated the Possibility of the Formation Mechanism of this New Templates.

Abstract: This paper puts forward a new method for the preparation of 99.999% high-purity alumina used for the LED underlay sapphire, which has above 99.999% high-purity aluminum atomized the active aluminum powder by the supersonic multistage cooling way, then makes the powder form the hydrate of the alumina through the hydrolyzing reaction, and finally gets 99.999% high-purity alumina by means of the calcinations and the follow-up granularity treatment. By the processing way, the reactant is only aluminum and water, and there is no other additive, which profitably keeps the product pure and completely satisfies the requirements of synthetic crystals while tested.

Abstract: Influence of SPD process realized by ECAP on structural formation and mechanical properties was searched. Samples after ECAP were heat treated at various temperature and time conditions. Investigation material bases were high purity aluminium and aluminium alloys EN AW 6082, EN AW 2014. The best material properties are describing in dependence on experimental conditions.

Abstract: High-Speed Centrifugal Compaction Process (HCP) is one of slip-using compacting method in which the compacts are obtained as sediments under huge centrifugal force. Compacting mechanism of the HCP differs from other slip using compacting methods. The unique compacting mechanism of the HCP leads a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, etc. Moreover, the most outstanding characteristics of the HCP can be found in homogeneous and flawless microstructure of the green compacts, because the process possesses an intrinsic defect removing function. That is, the defect inducing matters in slips (powder aggregates, inclusions, bubbles) are removed from the main part of the compact by the classification effect of centrifuge, and therefore the HCP alumina exhibits superior sinterabiliy and higher strength and hardness than most other aluminas. Many of the advantageous characteristics of the HCP can be improved with a higher centrifugal force.

Abstract: High purity aluminum (99.99% purity) was severely deformed by accumulative roll-bonding (ARB) to a thickness reduction of 98.4%. Quantitative microstructural characterization of the deformed sample was carried out by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). EBSD scans at various locations from the sample surface to the mid-thickness revealed a fairly uniform and equiaxed structure, although a small fraction of an elongated structure parallel to rolling direction (RD) was also observed. Misorientation angle distributions for grain boundaries of which misorientation angle was larger than 2° were evaluated by EBSD, showing that more than 70% of the boundaries were high-angle ones (>15°). More detailed structural features, such as low-angle boundaries (<2°) and dislocations between boundaries were characterized by TEM. The TEM results indicated that about 17% of the boundaries have misorientations <2° and that the fraction of high-angle boundaries is about 52%. An estimated yield strength based on the structural parameters determined by TEM was in good agreement with the measured value.

Abstract: Micro-orientation data of a high purity Al rolled up to total thickness reduction of 80% at room temperature were determined using SEM-EBSD technique, conceptions of describing substructure information, such as subgrain misorientation (θcry), and average misorientation (θenv) of circumjacent subgrains for a special subgrain, etc., were suggested and corresponding GCDP-OI soft package was developed. It is found that the subgrains sizes increase rapidly from about 2 to 7 μm with increasing misorientations from 1° to 15°, and the total number frequency of which is more than 95%. However, taking into account local features of subgrais, whose sizes for Dcry/Denv > 1 are 2 times larger than that for Dcry/Denv < 1 on the same misorientation levels below 20°, and the relationships between misorientations and sizes are consistent with that if Dcry/Denv > 1, θcry/θenv > 1, vice versa.

Abstract: It makes use of that excellent nature, high purity aluminum is being used as a function material in the electron, the high technology industry and information. Generally that material is molded as a slab, and processed through such as metal rolling is given after that, and it is being made. It is increase demand that it use for condenser. Condenser capacity is increase by making a (100) oriented cube texture crystal. It is known effective to increase a solid solubility of iron to aluminum that make increase the condenser capacity. Therefore, the cooling rate of Al-10,100 and 1000ppm content Fe was controlled by single roller equipment. Research was done about the relations of the amount of solid solubility of iron to aluminum and the cooling rate. It is result that the amount of solid solubility of iron to aluminum becomes 800ppm at the cooling rate of 2×103 K/s. When the cooling rate rises, the amount of solid solubility increases. The change appears in the separation thing as well because the amount of iron changes by this when the cooling rate is high. When iron is solid solubled in aluminum, it is bigger than the case of solid solubility formed by other general metal elements. Hardness is four times rose more than pure aluminum by solid solubility of iron to aluminum about 800ppm.