The Evolution of Homogeneity during Processing of Aluminium Alloys by HPT

2010 ◽  
Vol 667-669 ◽  
pp. 277-282 ◽  
Author(s):  
Saleh N. Alhajeri ◽  
Megumi Kawasaki ◽  
Nong Gao ◽  
Terence G. Langdon
Keyword(s):  
Aluminium Alloys ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Rapid Evolution ◽  
Mg Alloy ◽  
Commercial Purity ◽  
Purity Aluminium ◽  
Significant Difference ◽  
Commercial Purity Aluminium ◽  
Rate Of Recovery

Disks of a commercial purity aluminium Al-1050 alloy and Al-1%Mg alloy were processed by high-pressure torsion (HPT) at room temperature for up to a maximum of 5 turns under a pressure of 6 GPa. Following processing, hardness measurements were recorded across the surfaces of the disks. These measurements showed low values of hardness at the center and high values near the edges of the disks and the hardness increased in both alloys with increasing numbers of turns. The evolution of homogeneity in hardness was rapid in Al-1050 compared to the Al-1%Mg alloy. After 5 turns of HPT under a pressure of 6 GPa, the hardness was fully homogeneous across the total surface of the Al-1050 disk whereas there was a region of lower hardness around the center of the Al-1%Mg disk. The results reveal the significant difference between both alloys where the higher rate of recovery in the Al-1050 alloy leads to a rapid evolution of the hardness homogeneity.

Recovery Kinetics in High Purity and Commercial Purity Aluminium Alloys

2013 ◽  
Vol 753 ◽  
pp. 235-238 ◽  
Author(s):  
Sindre Bunkholt ◽  
Knut Marthinsen ◽  
Erik Nes
Keyword(s):  
Solid Solution ◽  
High Purity ◽  
Aluminium Alloys ◽  
Electron Backscatter Diffraction ◽  
Commercial Purity ◽  
Boundary Misorientation ◽  
Purity Aluminium ◽  
Recovery Mechanisms ◽  
Commercial Purity Aluminium ◽  
Ebsd Technique

Motivated by improving current softening models for recycle friendly alloys, softening was investigated in high purity and commercial purity aluminium alloys. Utilizing the electron backscatter diffraction (EBSD) technique, orientation dependent sub-grain growth was characterized with respect to grain size and average boundary misorientation. In the high purity alloys, small additions of Mn in solid solution slowed down the recovery kinetics. The recovery mechanisms were however not altered, but recovery kinetics were found to be orientation dependent. The presence of high angle grain boundaries or transition bands, i.e. large and sharp orientation gradients, seemed to change the growth from slow and continuous to a faster and discontinuous process. This was typical for Cube and Goss, while weak, short and long range orientations gradients observed in Copper, S and Brass, did not alter growth which was slow and continuous. Before detailed studies of recovery of the commercial purity alloy were initiated, a rather slow recovery was observed and further investigated. Preliminary results indicate that iron in solid solution is dramatically slowing down the kinetics but can form clusters by an intermediate annealing in order to speed up recovery.

scholarly journals Orientation Independent and Dependent Subgrain Growth During Iso-Thermal Annealing of High-Purity and Commercial Purity Aluminium

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1032
Author(s):  
Bunkholt ◽  
Nes ◽  
Marthinsen
Keyword(s):  
High Purity ◽  
Electron Backscatter Diffraction ◽  
Subgrain Size ◽  
Alloy System ◽  
Commercial Purity ◽  
Boundary Misorientation ◽  
Subgrain Growth ◽  
Purity Aluminium ◽  
Commercial Purity Aluminium ◽  
High Purity Aluminium

The orientation dependence on recovery has been studied in cold-rolled and annealed polycrystalline high-purity aluminium (99.99 wt%), binary Al-0.25Mn and commercial purity aluminium. The growth mechanisms were found to be independent of the alloy system and the microchemistry only influences the coarsening kinetics. Orientation-dependent subgrain growth, mainly studied in high-purity aluminium and measured in lamellar bands of uniform orientation, occurs in three distinct ways, depending of the size of the local orientation gradients. Following the evolution in average subgrain size and boundary misorientation by detailed electron backscatter diffraction (EBSD) characterization during annealing, it was found that the rate of subgrain growth in Cube- and Goss-oriented grains were faster than in the typical deformation texture components, particularly after an incubation time when discontinuous subgrain growth occurs. In commercial purity aluminium, general orientation-independent subgrain growth is faster than the orientation-dependent growth because more growth occurs in regions near high-angle grain boundaries separating differently oriented lamellar bands. It appears as if subgrains misoriented by more than 3.5° have a growth advantage over less misoriented subgrains, typically in the interior of lamellar bands. While the average boundary misorientations are decreasing, the individual boundary misorientations are increasing.

Mechanical properties and microstructure of ultrafine grained commercial purity aluminium prepared by cryo-hydrostatic extrusion

2017 ◽  
Vol 695 ◽  
pp. 178-192 ◽  
Author(s):  
Wacek Pachla ◽  
Mariusz Kulczyk ◽  
Julita Smalc-Koziorowska ◽  
Monika Wróblewska ◽  
Jacek Skiba ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hydrostatic Extrusion ◽  
Commercial Purity ◽  
Ultrafine Grained ◽  
Purity Aluminium ◽  
Commercial Purity Aluminium
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