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Title: Defect formation by pristine indenter at the initial stage of nanoindentation

Nano-indentation is a sophisticated method to characterize mechanical properties of materials. This method samples a very small amount of material during each indentation. Therefore, this method is extremely useful to measure mechanical properties of nano-materials. The measurements using nanoindentation is very sensitive to the surface topology of the indenter and the indenting surfaces. The mechanisms involved in the entire process of nanoindentation require an atomic level understanding of the interplay between the indenter and the substrate. In this paper, we have used atomistic simulation methods with empirical potentials to investigate the effect of various types of pristine indenter on the defect nucleation and growth. Using molecular dynamics simulations, we have predicted the load-depth curve for conical, vickers, and sperical tip. The results are analyzed based on the coherency between the indenter tip and substrate surface for a fixed depth of 20 Å. The depth of defect nucleation and growth is observed to be dependent on the tip geometry. A tip with larger apex angle nucleates defects at a shallower depth. However, the type of defect generated is dependent on the crystalline orientation of the tip and substrate. For coherent systems, prismatic loops were generated, which released into the substrate along themore » close-packed directions with continued indentation. For incoherent systems, pyramidal shaped dislocation junctions formed in the FCC systems and disordered atomic clusters formed in the BCC systems. These defect nucleation and growth process provide the atomistic mechanisms responsible for the observed load-depth response during nanoindentation.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [2] ;  [2]
  1. Department of Materials Science and Engineering, National Cheng Kung University, Tainan City, 70101 Taiwan (China)
  2. (China)
  3. Nuclear and Radiological Engineering Program, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)
Publication Date:
OSTI Identifier:
22258720
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 21; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMIC CLUSTERS; BCC LATTICES; CONNECTORS; DEFECTS; DISLOCATIONS; ELECTRIC CONTACTS; FCC LATTICES; MECHANICAL PROPERTIES; MOLECULAR DYNAMICS METHOD; NUCLEATION; SIMULATION; SUBSTRATES; TOPOLOGY