Annealing Behavior of Nanostructured Aluminum Produced by Cold Rolling to Ultrahigh Strains
- PDF / 675,734 Bytes
- 11 Pages / 593.972 x 792 pts Page_size
- 73 Downloads / 204 Views
TRODUCTION
DUE to the industrial interest in the production of aluminum sheet and foil, a considerable amount of research has been carried out over a number of years on the texture and microstructure evolution during annealing of deformed aluminum.[1–10] Much of this work has been focused on material deformed to medium to high strains (up to 95 pct reduction), where annealing results in both recovery and recrystallization. In recent years, however, there has been an additional interest in exploring the effect of deformation to ultrahigh strains, with the objective of producing nanostructured metals and alloys with very high strengths.[11–17] Such high strains may be achieved by many different deformation processes, and metals with very high strength have been produced. However, the formability of such materials is generally very poor on account of their limited ductility, and an optimization is therefore required through a combination of deformation and annealing treatments. W.Q. CAO, formerly Postdoctoral Student, Department of Materials Science and Engineering, Tsinghua University, is Postdoctoral Researcher, Department of Materials Engineering, Monash University, Clayton, 3800, Victoria, Australia. A. GODFREY, Professor, is with the Center for Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, Peoples Republic of China. Contact e-mail: agtsinghua@ excite.com Q. LIU, Professor, formerly with the Department of Materials Science and Engineering, Tsinghua University, is with the School of Materials Science and Engineering, Chongqing University, 400030, Chongqing, People’s Republic of China. N. HANSEN, Senior Scientist, is with the Center for Fundamental Research: Metal Structures in Four Dimensions, Risø DTU National Laboratory for Sustainable Energy, Roskilde, Denmark. Manuscript submitted November 28, 2007. Article published online November 19, 2008 204—VOLUME 40A, JANUARY 2009
As a consequence, there is at present much interest in the annealing behavior of metals and alloys deformed to very high strains. In this context, it has been suggested in a number of studies that for metals deformed beyond a certain strain, a transition in the annealing behavior occurs from the conventional recrystallization (i.e., nucleation and growth) process typically observed for samples deformed to medium and large strain[5] to a process of extended recovery, where a continuous (uniform) coarsening of the microstructure is reported.[19,20] (Note that various terms have been used for these processes,[20] for example conventional recrystallization and extended recovery have also been named discontinuous recrystallization and continuous recrystallization, respectively.) In this article, we explore the possibility of such a transition in the annealing behavior using samples deformed to nominal strains in the range from 0.8 to 4.8. In common with other similar studies, the main experimental technique used in this study was electron backscatter diffraction (EBSD) in the scanning electron
Data Loading...
