Recovery Kinetics in High Purity and Commercial Purity Aluminium Alloys

2013 ◽  
Vol 753 ◽  
pp. 235-238 ◽  
Author(s):  
Sindre Bunkholt ◽  
Knut Marthinsen ◽  
Erik Nes

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.

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1032
Author(s):  
Bunkholt ◽  
Nes ◽  
Marthinsen

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.


2010 ◽  
Vol 667-669 ◽  
pp. 277-282 ◽  
Author(s):  
Saleh N. Alhajeri ◽  
Megumi Kawasaki ◽  
Nong Gao ◽  
Terence G. Langdon

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.


2014 ◽  
Vol 783-786 ◽  
pp. 282-287
Author(s):  
Gui Lin Wu

The microstructural and textural evolutions during annealing of a highly strained (ε=4.0) commercial purity aluminium (AA1200) were followed by electron backscatter diffraction (EBSD). Boundary spacings were analyzed for crystallites of different crystallographic orientations. It was found that initially during the annealing the microstructural evolution is dominated by recovery of the highly strained microstructure, while later the microstructure consists of identifiable grains nucleating and growing at the expense of deformed and recovered matrix. No much texture change occursduring early stages of annealing, whereas a cube texture evolves and dominates after complete recrystallization.


2013 ◽  
Vol 46 (1) ◽  
pp. 216-223
Author(s):  
Shan-Rong Zhao ◽  
Hai-Jun Xu ◽  
Rong Liu ◽  
Qin-Yan Wang ◽  
Xian-Yu Liu

Snowflake-shaped dendrites of β-eucryptite–β-quartz solid solution were artificially crystallized in a matt glaze, and the crystallographic orientation of the dendrites was analysed by the electron backscatter diffraction (EBSD) technique. The six branches of a snowflake-shaped dendrite in the plane (0001) are along 〈110〉. From the orientation determination, a twin relationship and a topotactic relationship between dendrites were found. The twin axes are [011], [0{\overline 1}1] and [210], and the twin planes perpendicular to the twin axes are ({\overline 1}2{\overline 1}2) and (1{\overline 2}12). From the reticular theory of twinning, it was calculated that the twin indexn= 2 and the obliquity ω = 3.2877°. The studied dendrite is a twin by reticular pseudomerohedry with low twin index and obliquity. In the topotactic growth, no twin elements have been found, but the three main crystallographic directions 〈001〉, 〈210〉 and 〈110〉 of the two dendritic crystals overlap each other. The degree of lattice coincidence between the two crystals in this topotactic growth is also discussed.


2017 ◽  
Vol 695 ◽  
pp. 178-192 ◽  
Author(s):  
Wacek Pachla ◽  
Mariusz Kulczyk ◽  
Julita Smalc-Koziorowska ◽  
Monika Wróblewska ◽  
Jacek Skiba ◽  
...  

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