Atomic-Level Observation of Disclination Dipoles in Mechanically Milled, Nanocrystalline Fe

• Published in: Science (American Association for the Advancement of Science) Vol. 295; no. 5564; pp. 2433 - 2435
• Main Authors: Murayama, M., Howe, J. M., Hidaka, H., Takaki, S.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 29.03.2002; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Alloys; Applied sciences; Atomic structure; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystals; Defects and impurities in crystals; microstructure; Deformation; Exact sciences and technology; Grain boundaries; Iron; Laboratory Equipment; Linear defects: dislocations, disclinations; Magnetic fields; Materials; Materials science; Metals. Metallurgy; Methods; Milling (Metals); Milling (Metalwork); Nanoscale materials and structures: fabrication and characterization; Observation; Physics; Plasticity; Plastics; Rotation; Scientific imaging; Structure of solids and liquids; crystallography; Iron; Plastic deformation; Experimental study; High-resolution methods; Mechanism; Dislocation dipoles; Mechanical treatment; Transmission electron microscopy; BCC lattices; Disclinations; Transition elements; Atomic structure; Nanocrystal
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1067430

Plastic deformation of materials occurs by the motion of defects known as dislocations and disclinations. High-resolution transmission electron microscopy was used to directly reveal the individual dislocations that constitute partial disclination dipoles in nanocrystalline, body-centered cubic iron that had undergone severe plastic deformation by mechanical milling. The mechanisms by which the formation and migration of such partial disclination dipoles during deformation allow crystalline solids to fragment and rotate at the nanometer level are described. Such rearrangements are important basic phenomena that occur during material deformation, and hence, they may be critical in the formation of nanocrystalline metals by mechanical milling and other deformation processes.