skip to main content

SciTech ConnectSciTech Connect

Title: Stochastic dislocation kinetics and fractal structures in deforming metals probed by acoustic emission and surface topography measurements

We demonstrate that the fractal dimension (FD) of the dislocation population in a deforming material is an important quantitative characteristic of the evolution of the dislocation structure. Thus, we show that peaking of FD signifies a nearing loss of uniformity of plastic flow and the onset of strain localization. Two techniques were employed to determine FD: (i) inspection of surface morphology of the deforming crystal by white light interferometry and (ii) monitoring of acoustic emission (AE) during uniaxial tensile deformation. A connection between the AE characteristics and the fractal dimension determined from surface topography measurements was established. As a common platform for the two methods, the dislocation density evolution in the bulk was used. The relations found made it possible to identify the occurrence of a peak in the median frequency of AE as a harbinger of plastic instability leading to necking. It is suggested that access to the fractal dimension provided by AE measurements and by surface topography analysis makes these techniques important tools for monitoring the evolution of the dislocation structure during plastic deformation—both as stand-alone methods and especially when used in tandem.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. Laboratory for the Physics of Strength of Materials and Intelligent Diagnostic Systems, Togliatti State University, Togliatti 445667 (Russian Federation)
  2. (Russian Federation)
  3. Laboratory of Hybrid Nanostructured Materials, NITU MISiS, Moscow 119490 (Russian Federation)
  4. (Australia)
Publication Date:
OSTI Identifier:
22303987
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; DEFORMATION; DENSITY; DISLOCATIONS; EMISSION; FRACTALS; INSTABILITY; INTERFEROMETRY; LOSSES; METALS; PLASTICITY; STOCHASTIC PROCESSES; STRAINS; SURFACES; VISIBLE RADIATION