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Title: In-situ visualization of stress-dependent bulk magnetic domain formation by neutron grating interferometry

The performance and degree of efficiency of industrial transformers are directly influenced by the magnetic properties of high-permeability steel laminations (HPSLs). Industrial transformer cores are built of stacks of single HPSLs. While the insulating coating on each HPSL reduces eddy-current losses in the transformer core, the coating also induces favorable inter-granular tensile stresses that significantly influence the underlying magnetic domain structure. Here, we show that the neutron dark-field image can be used to analyze the influence of the coating on the volume and supplementary surface magnetic domain structures. To visualize the stress effect of the coating on the bulk domain formation, we used an uncoated HPSL and stepwise increased the applied external tensile stress up to 20 MPa. We imaged the domain configuration of the intermediate stress states and were able to reproduce the original domain structure of the coated state. Furthermore, we were able to visualize how the applied stresses lead to a refinement of the volume domain structure and the suppression and reoccurrence of supplementary domains.
Authors:
 [1] ;  [2] ;  [3] ; ; ; ; ;  [1] ;  [4] ;  [5] ;  [2]
  1. Paul Scherrer Institut, Laboratory for Neutron Scattering and Imaging, CH-5232 Villigen (Switzerland)
  2. (Switzerland)
  3. Fraunhofer IWS Dresden, Laser Ablation and Cutting, D-01277 Dresden (Germany)
  4. Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Helmholzstr.20, D-01069 Dresden, Germany and Institute for Materials Science, University of Technology, D-01069 Dresden (Germany)
  5. École Polytechnique Fédérale de Lausanne, NXMM Laboratory, IMX, CH-1015 Lausanne (Switzerland)
Publication Date:
OSTI Identifier:
22489246
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 1; Other Information: (c) 2016 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; DIFFRACTION GRATINGS; DOMAIN STRUCTURE; EDDY CURRENTS; IMAGES; INTERFEROMETRY; MAGNETIC PROPERTIES; NEUTRONS; PERMEABILITY; PRESSURE RANGE MEGA PA; STEELS; STRESSES; SURFACES; TRANSFORMERS