An investigation of grain boundaries in submicrometer-grained Al-Mg solid solution alloys using high-resolution electron
- PDF / 1,307,501 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 13 Downloads / 138 Views
MATERIALS RESEARCH
Welcome
Comments
Help
An investigation of grain boundaries in submicrometer-grained Al-Mg solid solution alloys using high-resolution electron microscopy Zenji Horita Department of Materials Science and Engineering, Faculty of Engineering 36, Kyushu University, Fukuoka 812, Japan
David J. Smith Center for Solid State Science and Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85287
Minoru Furukawa Department of Technology, Fukuoka University of Education, Munakata, Fukuoka 811-41, Japan
Minoru Nemoto Department of Materials Science and Engineering, Faculty of Engineering 36, Kyushu University, Fukuoka 812, Japan
Ruslan Z. Valiev Institute for Metals Superplasticity Problems, Russian Academy of Sciences, Ufa 450001, Russia
Terence G. Langdon Departments of Materials Science and Mechanical Engineering, University of Southern California, Los Angeles, California 90089-1453 (Received 4 August 1995; accepted 28 March 1996)
High-resolution electron microscopy was used to examine the structural features of grain boundaries in Al–1.5% Mg and Al –3% Mg solid solution alloys produced with submicrometer grain sizes using an intense plastic straining technique. The grain boundaries were mostly curved or wavy along their length, and some portions were corrugated with regular or irregular arrangements of facets and steps. During exposure to high-energy electrons, grain boundary migration occurred to reduce the number of facets and thus to reduce the total boundary energy. The observed features demonstrate conclusively that the grain boundaries in these submicrometer-grained materials are in a high-energy nonequilibrium configuration.
I. INTRODUCTION
Recent studies have shown that submicrometergrained (SMG) structures can be produced in a range of pure metals, metallic alloys, and semiconductors by imposing intense plastic strain.1–4 Although the grain sizes produced in this way are usually in the submicron range of ,100–200 nm, some nanocrystalline structures have been fabricated with grain sizes of ,50 nm.5 The production of SMG structures by intense plastic straining offers two significant advantages over other techniques such as inert gas condensation and coalescence.6 First, it is possible to produce large bulk samples. Second, these samples are free from any residual porosity. Careful experiments have established several similarities between the SMG materials and nanocrystalline samples prepared by inert gas condensation,6 including changes in some fundamental properties of the materials 1880
http://journals.cambridge.org
J. Mater. Res., Vol. 11, No. 8, Aug 1996
Downloaded: 29 May 2014
that are generally considered to be structure-insensitive such as the elastic modulus,7 the Debye temperature,8 and the Curie temperature.9 The precise origin of these changes is not yet understood but they may arise either from the presence of the very small grain size or from the specific nature of the grain boundary structure. An earlier report described an examination by tran
Data Loading...
